Name: utilizing the precision-cut lung slice to study the contractile regulation of airway and intrapulmonary arterial smooth muscle
Uploaded: 2022-05-05T15:00:00
Description: Watch this Scientific Journal Video about Utilizing the Precision-Cut Lung Slice to Study the Contractile Regulation of Airway and Intrapulmonary Arterial Smooth Muscle at JoVE.com

This work is supported by NIH grants, K08135443 (Y.B), 1R01HL132991 (X.A).

All animal care was in accordance with the guidelines of the Institutional Animal Care and Use Committee of Massachusetts General Hospital. Wild-type C57/B6 male mice, 8 weeks of age, were used for the present study.
1. Experimental preparation
<ol>
	<li>Prepare the working solution.
	<ol>
		<li>Prepare 1x Hank&#39;s Balanced Salt Solution (HBSS, with Ca2+ and Mg2+, and pH balanced with 20 mM HEPES, see Table of Materials). Use the HBSS...

<ol>
	<li>Prakash, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emerging+concepts+in+smooth+muscle+contributions+to+airway+structure+and+function:+implications+for+health+and+disease.">Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease.</a> American Journal of Physiology Lung Cellular and Molecular Physiology. 311 (6), 1113-1140 (2016).</li><li>Lechartier, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phenotypic+diversity+of+vascular+smooth+muscle+cells+in+pulmonary+arterial+hypertension:+implications+for+therapy.">Phenotypic diversity of vascular smooth muscle cells in pulmonary arterial hypertension: implications for therapy.</a> Chest. 161 (1), 219-231 (2022).</li><li>Doeing, D. C., Solway, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Airway+smooth+muscle+in+the+pathophysiology+and+treatment+of+asthma.">Airway smooth muscle in the pathophysiology and treatment of asthma.</a> Journal of Applied Physiology. 114 (7), 834-843 (2013).</li><li>McGovern, T. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+respiratory+system+mechanics+in+mice+using+the+forced+oscillation+technique.">Evaluation of respiratory system mechanics in mice using the forced oscillation technique.</a> Journal of Visualized Experiments: JoVE. (75), e50172 (2013).</li><li>Bikou, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+and+characterization+of+pulmonary+hypertension+in+mice+using+the+hypoxia/SU5416+model.">Induction and characterization of pulmonary hypertension in mice using the hypoxia/SU5416 model.</a> Journal of Visualized Experiments: JoVE. (160), e59252 (2020).</li><li>Stenmark, K. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+and+diverse+changes+in+the+functional+properties+of+vascular+smooth+muscle+cells+in+pulmonary+hypertension.">Dynamic and diverse changes in the functional properties of vascular smooth muscle cells in pulmonary hypertension.</a> Cardiovascular Research. 114 (4), 551-564 (2018).</li><li>Bai, Y., Zhang, M., Sanderson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contractility+and+Ca2++signaling+of+smooth+muscle+cells+in+different+generations+of+mouse+airways.">Contractility and Ca2+ signaling of smooth muscle cells in different generations of mouse airways.</a> American Journal of Respiratory Cell and Molecular Biology. 36 (1), 122-130 (2007).</li><li>Chin, L. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+airway+smooth+muscle+is+structurally+and+mechanically+similar+to+that+of+other+species.">Human airway smooth muscle is structurally and mechanically similar to that of other species.</a> The European Respiratory Journal. 36 (1), 170-177 (2010).</li><li>Wang, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammatory+mediators+mediate+airway+smooth+muscle+contraction+through+a+G+protein-coupled+receptor-transmembrane+protein+16A-voltage-dependent+Ca(2+)+channel+axis+and+contribute+to+bronchial+hyperresponsiveness+in+asthma.">Inflammatory mediators mediate airway smooth muscle contraction through a G protein-coupled receptor-transmembrane protein 16A-voltage-dependent Ca(2+) channel axis and contribute to bronchial hyperresponsiveness in asthma.</a> The Journal of Allergy and Clinical Immunology. 141 (4), 1259-1268 (2018).</li><li>Currigan, D. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vasoconstrictor+responses+to+vasopressor+agents+in+human+pulmonary+and+radial+arteries:+an+in+vitro+study.">Vasoconstrictor responses to vasopressor agents in human pulmonary and radial arteries: an in vitro study.</a> Anesthesiology. 121 (5), 930-936 (2014).</li><li>Halayko, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Divergent+differentiation+paths+in+airway+smooth+muscle+culture:+induction+of+functionally+contractile+myocytes.">Divergent differentiation paths in airway smooth muscle culture: induction of functionally contractile myocytes.</a> The American Journal of Physiology. 276 (1), 197-206 (1999).</li><li>Worth, N. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+smooth+muscle+cell+phenotypic+modulation+in+culture+is+associated+with+reorganisation+of+contractile+and+cytoskeletal+proteins.">Vascular smooth muscle cell phenotypic modulation in culture is associated with reorganisation of contractile and cytoskeletal proteins.</a> Cell Motility and the Cytoskeleton. 49 (3), 130-145 (2001).</li><li>Sanderson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+lung+physiology+in+health+and+disease+with+lung+slices.">Exploring lung physiology in health and disease with lung slices.</a> Pulmonary Pharmacology and Therapeutics. 24 (5), 452-465 (2011).</li><li>Placke, M. E., Fisher, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+peripheral+lung+organ+culture-a+model+for+respiratory+tract+toxicology.">Adult peripheral lung organ culture-a model for respiratory tract toxicology.</a> Toxicology and Applied Pharmacology. 90 (2), 284-298 (1987).</li><li>Fisher, G. L., Placke, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+models+of+lung+toxicity.">In vitro models of lung toxicity.</a> Toxicology. 47 (1-2), 71-93 (1987).</li><li>Perez, J. F., Sanderson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+contraction+of+smooth+muscle+cells+of+intrapulmonary+arterioles+is+determined+by+the+frequency+of+Ca2++oscillations+induced+by+5-HT+and+KCl.">The contraction of smooth muscle cells of intrapulmonary arterioles is determined by the frequency of Ca2+ oscillations induced by 5-HT and KCl.</a> The Journal of General Physiology. 125 (6), 555-567 (2005).</li><li>Li, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preserving+airway+smooth+muscle+contraction+in+precision-cut+lung+slices.">Preserving airway smooth muscle contraction in precision-cut lung slices.</a> Scientific Reports. 10 (1), 6480 (2020).</li><li>Sanderson, M. J., Parker, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Video-rate+confocal+microscopy.">Video-rate confocal microscopy.</a> Methods in Enzymology. 360, 447-481 (2003).</li><li>Kolbe, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+cytokine+induction+upon+pseudomonas+aeruginosa+infection+in+murine+precision+cut+lung+slices+depends+on+sensing+of+bacterial+viability.">Early cytokine induction upon pseudomonas aeruginosa infection in murine precision cut lung slices depends on sensing of bacterial viability.</a> Frontiers in Immunology. 11, 598636 (2020).</li><li>Perez, J. F., Sanderson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+frequency+of+calcium+oscillations+induced+by+5-HT,+ACH,+and+KCl+determine+the+contraction+of+smooth+muscle+cells+of+intrapulmonary+bronchioles.">The frequency of calcium oscillations induced by 5-HT, ACH, and KCl determine the contraction of smooth muscle cells of intrapulmonary bronchioles.</a> The Journal of General Physiology. 125 (6), 535-553 (2005).</li><li>Rosner, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Airway+contractility+in+the+precision-cut+lung+slice+after+cryopreservation.">Airway contractility in the precision-cut lung slice after cryopreservation.</a> American Journal of Respiratory Cell and Molecular Biology. 50 (5), 876-881 (2014).</li><li>Bai, Y., Sanderson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+the+Ca2++sensitivity+of+airway+smooth+muscle+cells+in+murine+lung+slices.">Modulation of the Ca2+ sensitivity of airway smooth muscle cells in murine lung slices.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 291 (2), 208-221 (2006).</li><li>Sanderson, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+microscopy.">Fluorescence microscopy.</a> Cold Spring Harbor Protocols. 10, 071795 (2014).</li><li>Sanderson, M. J., Bai, Y., Perez-Zoghbi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ca(2+)+oscillations+regulate+contraction+of+intrapulmonary+smooth+muscle+cells.">Ca(2+) oscillations regulate contraction of intrapulmonary smooth muscle cells.</a> Advances in Experimental Medicine and Biology. 661, 77-96 (2010).</li><li>Perez-Zoghbi, J. F., Bai, Y., Sanderson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nitric+oxide+induces+airway+smooth+muscle+cell+relaxation+by+decreasing+the+frequency+of+agonist-induced+Ca2++oscillations.">Nitric oxide induces airway smooth muscle cell relaxation by decreasing the frequency of agonist-induced Ca2+ oscillations.</a> The Journal of General Physiology. 135 (3), 247-259 (2010).</li><li>Lam, M., Lamanna, E., Bourke, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+airway+smooth+muscle+contraction+in+health+and+disease.">Regulation of airway smooth muscle contraction in health and disease.</a> Advances in Experimental Medicine and Biology. 1124, 381-422 (2019).</li><li>Patel, K. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+acetylcholine+receptor+M3+prevents+the+progression+of+airway+hyperreactivity+in+a+mouse+model+of+childhood+asthma.">Targeting acetylcholine receptor M3 prevents the progression of airway hyperreactivity in a mouse model of childhood asthma.</a> FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology. 31 (10), 4335-4346 (2017).</li><li>Aven, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+NT4/TrkB-dependent+increase+in+innervation+links+early-life+allergen+exposure+to+persistent+airway+hyperreactivity.">An NT4/TrkB-dependent increase in innervation links early-life allergen exposure to persistent airway hyperreactivity.</a> FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology. 28 (2), 897-907 (2014).</li><li>Liu, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+precision+cut+lung+slices+as+a+translational+model+for+the+study+of+lung+biology.">Use of precision cut lung slices as a translational model for the study of lung biology.</a> Respiratory Research. 20 (1), 162 (2019).</li><li>Wu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+lung+tissue+slice+culture.">Mouse lung tissue slice culture.</a> Methods in Molecular Biology. 1940, 297-311 (2019).</li><li>Bai, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD38+plays+an+age-related+role+in+cholinergic+deregulation+of+airway+smooth+muscle+contractility.">CD38 plays an age-related role in cholinergic deregulation of airway smooth muscle contractility.</a> The Journal of Allergy and Clinical Immunology. 6749 (21), 01760-01767 (2021).</li><li>Khan, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+integrated+multiomic+and+quantitative+label-free+microscopy-based+approach+to+study+pro-fibrotic+signalling+in+ex+vivo+human+precision-cut+lung+slices.">An integrated multiomic and quantitative label-free microscopy-based approach to study pro-fibrotic signalling in ex vivo human precision-cut lung slices.</a> The European Respiratory Journal. 58 (1), (2021).</li><li>Kennedy, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+rhinovirus+39+infection+on+airway+hyperresponsiveness+to+carbachol+in+human+airways+precision+cut+lung+slices.">Effects of rhinovirus 39 infection on airway hyperresponsiveness to carbachol in human airways precision cut lung slices.</a> The Journal of Allergy and Clinical Immunology. 141 (5), 1887-1890 (2018).</li><li>Bai, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryopreserved+Human+precision-cut+lung+slices+as+a+bioassay+for+live+tissue+banking.+a+viability+study+of+bronchodilation+with+bitter-taste+receptor+agonists.">Cryopreserved Human precision-cut lung slices as a bioassay for live tissue banking. a viability study of bronchodilation with bitter-taste receptor agonists.</a> American Journal of Respiratory Cell and Molecular Biology. 54 (5), 656-663 (2016).</li><li>Mondo&#241;edo, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+high-throughput+system+for+cyclic+stretching+of+precision-cut+lung+slices+during+acute+cigarette+smoke+extract+exposure.">A high-throughput system for cyclic stretching of precision-cut lung slices during acute cigarette smoke extract exposure.</a> Frontiers in Physiology. 11, 566 (2020).</li><li>Davidovich, N., Huang, J., Margulies, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reproducible+uniform+equibiaxial+stretch+of+precision-cut+lung+slices.">Reproducible uniform equibiaxial stretch of precision-cut lung slices.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 304 (4), 210-220 (2013).</li><li>Ram-Mohan, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+traction+microscopy+to+quantify+muscle+contraction+within+precision-cut+lung+slices.">Tissue traction microscopy to quantify muscle contraction within precision-cut lung slices.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 318 (2), 323-330 (2020).</li></ol>

The preparation of PCLS involves several critical steps. First, it is essential to inflate the lung lobe homogeneously to avoid the variation of tissue stiffness from uneven agarose distribution. As the liquid agarose rapidly gels in thin catheters or airways at a temperature below 37 &#176;C, the resultant filling defect in the distal lung field could increase the disparity of lung tissue stiffness and cause tissue tearing during the vibratome section. Therefore, keeping the low-melting agarose solution at 42 &#176;C in...

Smooth muscle cell (SMC) is a major structural cell type in the lung, primarily residing in the media wall of airways and pulmonary vessels. SMCs contract to alter the luminal caliber, thus regulating air and blood flow1,2. Therefore, contractile regulation of SMCs is essential to maintain the homeostasis of air ventilation and pulmonary circulation. In contrast, aberrant SMC contractility provokes obstructive airway or pulmonary vascular diseases like asthma and pulmonary arterial hypertension. However, the functional assessment of lung SMCs has been challenged by limited access to the lung tissue, especially those small airways and microvessels in the distal part of the lung2,3. Current solutions resort to indirect assays, such as measuring airflow resistance by Flexivent to reflect airway constriction, and checking pulmonary arterial blood pressure by right heart catheterization to assess pulmonary vasocontraction4,5. However, these indirect assays have multiple disadvantages, such as being confounded by structural factors, failing to capture the spatial diversity of airway or vascular responses in the whole lung scale6,7, and unfitting for the mechanistic study of contractile regulation at the cellular level. Therefore, alternative approaches using isolated primary cells, trachea/bronchi muscle strips8,9, or large vascular segments10 have been applied for the SMC study in vitro. Nevertheless, these methods also have limitations. For example, a quick phenotypical adaptation of primary SMCs in the culture condition11,12 makes it problematic to extrapolate findings from cell culture to in vivo settings. In addition, the contractile phenotype of SMCs in the isolated proximal airway or vascular segments may not represent the SMCs in the distal lung6,7. Moreover, the muscle force measurement at the tissue level remains dissociated from molecular and cellular events that are essential for mechanistic insight into contractile regulation.
Precision-cut lung slice (PCLS), a live lung tissue section, provides an ideal ex vivo tool to characterize pulmonary SMCs in a near in vivo microenvironment (i.e., preserved multi-cellular architecture and interaction)13. Since Drs. Placke and Fisher first introduced the preparation of lung slices from agarose-inflated rat and hamster lungs in the 1980s14,15, this technique has been advanced continuously to provide PCLSs with higher quality and greater versatility for biomedical research. One significant improvement is the enhancement of pulmonary arterial preservation by gelatin infusion in addition to lung inflation with agarose via the trachea. As a result, both the airway and pulmonary arteries are kept intact in the PCLS for ex vivo assessement16. Furthermore, the PCLS is viable for a prolonged time in culture. For instance, mouse PCLSs had no significant change in cell viability and metabolism for a minimum of 12 days in culture, as well as, they retained airway contractility for up to 7 days17. In addition, PCLS keeps different-sized airways or vessels for contraction and relaxation assays. Moreover, intracellular Ca2+ signaling of SMCs, the determinant factor of cell contractility, can be assayed with Ca2+ reporter dyes imaged by a confocal or 2-photon microscope13.
Considering the extensive application of the mouse model in lung research, a detailed protocol is described here for preparing mouse PCLS with intact airways and intrapulmonary arteries for ex vivo lung research. Using the prepared PCLSs, we subsequently demonstrated how to evaluate the airway and pulmonary arterial responses to constrictive or relaxant stimuli. In addition, the method of loading the PCLS with Ca2+ reporter dye and then imaging Ca2+ signaling of SMCs associated with contractile or relaxant responses are also described.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1 mL syringe</td>
			<td>BD</td>
			<td>309626</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL sterile centrifuge tubes</td>
			<td>Celltreat</td>
			<td>229411</td>
			<td></td>
		</tr>
		<tr>
			<td>3 mL syringe</td>
			<td>BD</td>
			<td>309585</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL sterile centrifuge tubes</td>
			<td>Celltreat</td>
			<td>229422</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetyl-beta-methacholine</td>
			<td>Millipore Sigma</td>
			<td>62-51-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-anitmycotic</td>
			<td>Thermo Fisher</td>
			<td>15240-062</td>
			<td></td>
		</tr>
		<tr>
			<td>CCD-camera</td>
			<td>Nikon</td>
			<td>Nikon Ds-Ri2 camera</td>
			<td></td>
		</tr>
		<tr>
			<td>Cover glassess</td>
			<td>Fisher Scientific</td>
			<td>12-548-5CP; 12-548-5PP</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryogenic vials</td>
			<td>Fisher Scientific</td>
			<td>430488</td>
			<td></td>
		</tr>
		<tr>
			<td>Custom-built laser scanning confocal microscope</td>
			<td></td>
			<td></td>
			<td>Details in Reference 18</td>
		</tr>
		<tr>
			<td>DMEM/F12</td>
			<td>Fisher Scientific</td>
			<td>MT-10-092-CM</td>
			<td></td>
		</tr>
		<tr>
			<td>Endothelin 1</td>
			<td>Millipore Sigma</td>
			<td>E7764</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine dissecting scissor</td>
			<td>Fisher Scientific</td>
			<td>NC9702861</td>
			<td></td>
		</tr>
		<tr>
			<td>Freezing container</td>
			<td>Sigma-Aldrich</td>
			<td>C1562</td>
			<td></td>
		</tr>
		<tr>
			<td>Gelatin from porcine skin</td>
			<td>Sigma-Aldrich</td>
			<td>9000-70-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Hanks&#39; Balanced Salt Solution (HBSS)</td>
			<td>Thermo Fisher</td>
			<td>14025092</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemostatic forcep</td>
			<td>Fisher Scientific</td>
			<td>16-100-117</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Thermo Fisher</td>
			<td>15630080</td>
			<td></td>
		</tr>
		<tr>
			<td>High vaccum silicone grease</td>
			<td>Fisher Scientific</td>
			<td>146355d</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl alcohol</td>
			<td>Sigma-Aldrich</td>
			<td>W292907-1KG-K</td>
			<td></td>
		</tr>
		<tr>
			<td>Metal washers</td>
			<td>Home Depot Product Authority</td>
			<td>800442</td>
			<td>Everbilt Flat Washers #10</td>
		</tr>
		<tr>
			<td>Micro-dissecting forcep</td>
			<td>Sigma-Aldrich</td>
			<td>F4142</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle scalp vein set (25 G)</td>
			<td>EXELINT</td>
			<td>26708</td>
			<td></td>
		</tr>
		<tr>
			<td>NOC-5</td>
			<td>Cayman Chemical</td>
			<td>16534</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon mesh</td>
			<td>Component Supply</td>
			<td>U-CMN-300</td>
			<td></td>
		</tr>
		<tr>
			<td>Oregon green 488 BAPTA-1 AM</td>
			<td>Life Technologies</td>
			<td>o-6807</td>
			<td></td>
		</tr>
		<tr>
			<td>Phase-contrast microscope</td>
			<td>Nikon</td>
			<td>Nikon Eclipse TS 100</td>
			<td></td>
		</tr>
		<tr>
			<td>Pluronic F-127</td>
			<td>Thermo Fisher</td>
			<td>P-6867</td>
			<td></td>
		</tr>
		<tr>
			<td>Razor blades</td>
			<td>Personna</td>
			<td></td>
			<td>Personna Double Edge Razor Blades in White Wrapper 100 count</td>
		</tr>
		<tr>
			<td>Sulfobromophthalein</td>
			<td>Sigma-Aldrich</td>
			<td>S0252</td>
			<td></td>
		</tr>
		<tr>
			<td>Superglue</td>
			<td>Krazy Glue</td>
			<td></td>
			<td>Krazy Glue, All purpose</td>
		</tr>
		<tr>
			<td>Ultrapure low melting point agarose</td>
			<td>Thermo Fisher</td>
			<td>16520050</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Precisionary</td>
			<td>VF 310-0Z</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibratome chilling block</td>
			<td>Precisionary</td>
			<td>SKU-VM-CB12.5-NC</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibratome specimen tube</td>
			<td>Precisionary</td>
			<td>SKU VF-SPS-VM-12.5-NC</td>
			<td></td>
		</tr>
		<tr>
			<td>Y shaped IV catheter</td>
			<td>BD</td>
			<td>383336</td>
			<td>BD Saf-T-Intima closed IV catheter</td>
		</tr>
	</tbody>
</table>

utilizing the precision-cut lung slice to study the contractile regulation of airway and intrapulmonary arterial smooth muscle

Smooth muscle cells (SMC) mediate the contraction of the airway and the intrapulmonary artery to modify airflow resistance and pulmonary circulation, respectively, hence playing a critical role in the homeostasis of the pulmonary system. Deregulation of SMC contractility contributes to several pulmonary diseases, including asthma and pulmonary hypertension. However, due to limited tissue access and a lack of culture systems to maintain in vivo SMC phenotypes, molecular mechanisms underlying the deregulated SMC contractility in these diseases remain fully identified. The precision-cut lung slice (PCLS) offers an ex vivo model that circumvents these technical difficulties. As a live, thin lung tissue section, the PCLS retains SMC in natural surroundings and allows in situ tracking of SMC contraction and intracellular Ca2+ signaling that regulates SMC contractility. Here, a detailed mouse PCLS preparation protocol is provided, which preserves intact airways and intrapulmonary arteries. This protocol involves two essential steps before subjecting the lung lobe to slicing: inflating the airway with low-melting-point agarose through the trachea and infilling pulmonary vessels with gelatin through the right ventricle. The PCLS prepared using this protocol can be used for bioassays to evaluate Ca2+-mediated contractile regulation of SMC in both the airway and the intrapulmonary arterial compartments. When applied to mouse models of respiratory diseases, this protocol enables the functional investigation of SMC, thereby providing insight into the underlying mechanism of SMC contractility deregulation in diseases.

Mouse PCLS preparation preserving intact intrapulmonary airways and arteries 
A 150 &#181;m thick PCLS was observed under the inverted phase-contrast microscope. In mouse lungs, conductive airways are accompanied by intrapulmonary arteries, running from the hilus to the peripheral lung. A representative pulmonary airway-artery bundle in a mouse PCLS is shown in Figure 2B. The airway can be easily identified by cuboidal epithelial cells with active cilial beating lining ...

Watch this Scientific Journal Video about Utilizing the Precision-Cut Lung Slice to Study the Contractile Regulation of Airway and Intrapulmonary Arterial Smooth Muscle at JoVE.com

Utilizing the Precision-Cut Lung Slice to Study the Contractile Regulation of Airway and Intrapulmonary Arterial Smooth Muscle

The present protocol describes preparing and utilizing mouse precision-cut lung slices to assess the airway and intrapulmonary arterial smooth muscle contractility in a nearly in vivo milieu.

Smooth muscle cells (SMC) mediate the contraction of the airway and the intrapulmonary artery to modify airflow resistance and pulmonary circulation, ...

The PCLS supports the assessment of airway and vascular smooth muscle cell activity in a nearly intact tissue environment, thereby providing an invaluable ex vivo model for pulmonary research. In term of smooth muscle research, the precision-cut lung slices preserve the in vivo phenotype of smooth muscle cells and their interaction with surrounding structures while allowing access to smooth muscle cell, which is important for a mechanistic study at the cellular level. To begin, place the mouse body on a dissection board in the supine position.Pin down the tail, front paws, and head with 25G syringe needles and sanitize the body with 70%ethanol. Open the chest cavity carefully along the sternum and bilateral inferior rib cage above the diaphragm. Then, point the sharp scissor tip away from the lung tissue and remove part of the bilateral ventral rib cages to expose the heart.Observe that the lung lobes collapse when the chest cavity opens. Use scissors to remove soft tissue in the mouse neck to expose the trachea. At the upper end of the trachea make a small hole of diameter 1.2 millimeters that should allow the passing of a 20G Y-shaped IV catheter tip.Connect one adapter port of the Y-shaped catheter with a 3 milliliter syringe prefilled with 0.5 milliliters of air and the other port with a 3 milliliter syringe prefilled with 2 milliliters of 1.5%agarose solution warmed to 42 degree Celsius. Inject agarose solution to fill the catheter and then push the catheter through the opening into the trachea to 5 to 8 millimeters. Slowly inject the agarose solution at a rate of 1 milliliter per 5 seconds.Observe that the lung expands along the proximal to distal axis. Stop the injection when the edge of each lung lobe is inflated. Then, inject 0.2 to 0.3 milliliters of air from the other syringe to push the residual agarose into conductive airways to the distal alveoli space.Clip closed the trachea with a pair of curved hemostatic forceps. To infill the pulmonary vasculature, fill a 1 milliliter syringe with warm 6%gelatin and connect it to a needle scalp vein catheter. Infill the catheter with gelatin solution and then puncture the right ventricle close to the inferior wall with the needle.Push the needle for 2 to 3 millimeters into the right ventricle and point the needle tip to the main pulmonary artery. Inject approximately 0.2 milliliters of gelatin solution slowly into the right ventricle and pulmonary arterial vessels. Keep the needle in place for five minutes after injection and cool the lung lobes by pouring ice cold HBSS solution on the heart and lung and place the body in a refrigerator.After this step, remove the mouse lung and heart from surrounding connective tissues with scissors. Then, separate each lung lobe and keep them in HBSS solution on ice. Trim the lung lobe and orient it such that the cutting direction is perpendicular to most airways from the hila to the lung surface.Attach it on top of the specimen column with super glue. Use a vibratome with a fresh thin razor blade to cut the lung lobe into 150 micrometer slices. Collect the slices in sterile Petri dishes prefilled with cold HBSS solution.Transfer the slices to Petri dishes filled with DMEM/F-12 culture medium. Place the dishes in a 37 degree Celsius incubator overnight before the experiments. Place a single precision-cut lung slice in each well of a 24 well culture plate filled with HBSS.Locate the slice in the middle of the well and then remove the HBSS solution with a pipette. Under a microscope, find the target airway and vessel in the slice and then cover it using a nylon mesh with a precut central hole to expose the targeted airway vessel area. Put a hollow metal washer on top of the mesh to hold the slices in place.Then, add 600 microliters of HBSS solution to submerge the slices. After 10 minutes, record the baseline images. To induce the airway or vascular contraction, cautiously remove the HBSS solution with a pipette and add 600 microliters of HBSS with an agonist.To prepare the calcium dye loading buffer, first dissolve 50 micrograms of dye with 10 microliters of DMSO and 0.2 grams of Pluronic F-12 powder in 1 milliliter of DMSO. Mix 10 microliters of the Pluronic solution with 10 microliters of calcium dye solution. Add this mixture to 2 milliliters of HBSS solution containing 200 micromolar of sulfobromophthalein.Then, place 15 precision-cut lung slices in 2 milliliters of calcium loading buffer and incubate at 30 degrees Celsius for one hour, followed by incubating in HBSS containing 100 micromolar sulfobromophthalein for 30 minutes. Then, place calcium dye loaded slices on a large cover glass. Fill high vacuum silicone grease in a 3 milliliter syringe attached to 18G blunt needle or a 200 microliter pipette tip and draw two parallel lines across the cover glass, above and below the slice.Cover the slice using an nylon mesh between two grease lines. Place the second cover glass on top of the mesh to generate a chamber. Add HBSS or a agonist solution into the chamber from one end with a pipette.Remove the fluid from the chamber by suctioning from the other end with tissue paper. The slice's chamber is now ready for the calcium imaging with a high speed laser scanning confocal microscope. Pulmonary airway artery bundles were observed in precision-cut lung slices of thickness 150 micrometers under a phase contrast microscope.At resting state, an airway was identified by cuboidal epithelial cells with a nearby pulmonary artery. Following exposure to methacholine, the luminal area was reduced while the pulmonary artery showed no response to the stimuli. Airway contractile responses were quantified by the percentage of luminal area reduction and showed similar dose dependent responses in one day and five day cultures.Upon reaching the peripheral lung field, the conductive airways branch into respiratory ducts and sacs surrounding the small intra-acinar arterioles. When exposed to endothelii both airways and pulmonary arteries constrict, which is followed by NOC-5 induced relaxation. At the resting state, the calcium dye loaded slices showed low fluorescence in the smooth muscle cells of the airway and vascular system under a confocal fluorescent microscope.Upon exposure to agonists, the calcium fluorescence intensity elevated in the cells and propagated to the entire cell, which correlated with the oscillatory signals. Technique wise, it is essential to inflate the lung with agarose homogeneously and avoid quick or excessive agarose injection. Always push air at the end to flush the agarose from the conductive airway to the distal alveoli space.In summary, using the precision-cut lung slices culture, one can provide a special variety of pulmonary smooth muscle functions and model the smooth muscle deregulation in vitro. It also provides an ideal platform to screen novo vasodilatory or bronchodilator medications.

utilizing-precision-cut-lung-slice-to-study-contractile-regulation

Research

JoVE Journal

Biology

Testing Visual Sensitivity to the Speed and Direction of Motion in Lizards

Testing visual sensitivity in any species provides basic information regarding behaviour, evolution, and ecology. However, testing specific features of the visual system provide more empirical evidence for functional applications. Investigation into the sensory system provides information about the sensory capacity, learning and memory ability, and establishes known baseline behaviour in which to gauge deviations (Burghardt, 1977). However, unlike mammalian or avian systems, testing for learning and memory in a reptile species is difficult. Furthermore, using an operant paradigm as a psychophysical measure of sensory ability is likewise as difficult. Historically, reptilian species have responded poorly to conditioning trials because of issues related to motivation, physiology, metabolism, and basic biological characteristics. Here, I demonstrate an operant paradigm used a novel model lizard species, the Jacky dragon (Amphibolurus muricatus) and describe how to test peripheral sensitivity to salient speed and motion characteristics. This method uses an innovative approach to assessing learning and sensory capacity in lizards. I employ the use of random-dot kinematograms (RDKs) to measure sensitivity to speed, and manipulate the level of signal strength by changing the proportion of dots moving in a coherent direction. RDKs do not represent a biologically meaningful stimulus, engages the visual system, and is a classic psychophysical tool used to measure sensitivity in humans and other animals. Here, RDKs are displayed to lizards using three video playback systems. Lizards are to select the direction (left or right) in which they perceive dots to be moving. Selection of the appropriate direction is reinforced by biologically important prey stimuli, simulated by computer-animated invertebrates.

Testing visual sensitivity in lizards using an operant conditioning paradigm that employs video playback of random-dot kinematograms and computer-generated invertebrates.

Testing visual sensitivity in any species provides basic information regarding behaviour, evolution, and ecology. However, testing specific features of ...

Computer-Generated Animal Model Stimuli

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In particular, understanding the constraints on visual signal design for communication has been of great interest. Traditional methods for investigating animal interactions have used basic observational techniques, staged encounters, or physical manipulation of morphology. Less intrusive methods have tried to simulate conspecifics using crude playback tools, such as mirrors, still images, or models. As technology has become more advanced, video playback has emerged as another tool in which to examine visual communication (Rosenthal, 2000). However, to move one step further, the application of computer-animation now allows researchers to specifically isolate critical components necessary to elicit social responses from conspecifics, and manipulate these features to control interactions. Here, I provide detail on how to create an animation using the Jacky dragon as a model, but this process may be adaptable for other species. In building the animation, I elected to use Lightwave  3D to alter object morphology, add texture, install bones, and provide comparable weight shading that prevents exaggerated movement. The animation is then matched to select motor patterns to replicate critical movement features. Finally, the sequence must rendered into an individual clip for presentation. Although there are other adaptable techniques, this particular method had been demonstrated to be effective in eliciting both conspicuous and social responses in staged interactions.

Computer-generated stimuli using the Jacky dragon as a model.

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In ...

Focal Ca2+ Transient Detection in Smooth Muscle

Ca2+ imaging of smooth muscle provides insight into cellular mechanisms that may not result in changes of membrane potential, such as the release of Ca2+ from internal stores, and allows multiple cells to be monitored simultaneously to assess, for example, coupling in syncytial tissue. Subcellular Ca2+ transients are common in smooth muscle, yet are difficult to measure accurately because of the problems caused by their stochastic occurrence, over an often wide field of view, in an organ that it prone to contract. To overcome this problem, we've developed a series of imaging protocols and analysis routines to acquire and then analyse, in an automated fashion, the frequency, location and amplitude of such events. While this approach may be applied in other contexts, our own work involves the detection of local purinergic Ca2+ transients for locating transmitter release with submicron resolution. 
ATP is released as a cotransmitter from autonomic nerves, where it binds to P2X1 receptors on the smooth muscle of the detrusor and vas deferens. Ca2+ enters the smooth muscle, resulting in purinergic neuroeffector Ca2+ transients (NCTs). The focal Ca2+ transients allow the optical monitoring of neurotransmitter release in a manner that has many advantages over electrophysiology. Apart from the greatly improved spatial resolution, optical recording has the additional advantage of allowing the recording of transmitter release from many distinguishable sites simultaneously. Furthermore, the optical plane of focus is easier to maintain or correct during long recording series than is the repositioning of an intracellular sharp microelectrode. 
In summary, a method for imaging of Ca2+ fluorescence is outlined which details the preparation of tissue, and the acquisition and analysis of data. We outline the use of several scripts for the analysis of such Ca2+ transients.

Focal Ca2+ Transient Detection in Smooth Muscle

Details methods for high-resolution Ca2+ imaging of smooth muscle within isolated organs, including: preparation of the tissue, image acquisition and data analysis.

Ca2+ imaging of smooth muscle provides insight into cellular mechanisms that may not result in changes of membrane potential, such as the release of Ca2+ ...

Heterotopic and Orthotopic Tracheal Transplantation in Mice used as Models to Study the Development of  Obliterative Airway Disease

Obliterative airway disease (OAD) is the major complication after lung transplantations that limits long term survival (1-7).
To study the pathophysiology, treatment and prevention of OAD, different animal models of tracheal transplantation in rodents have been developed (1-7). Here, we use two established models of trachea transplantation, the heterotopic and orthotopic model and demonstrate their advantages and limitations.
For the heterotopic model, the donor trachea is wrapped into the greater omentum of the recipient, whereas the donor trachea is anastomosed by end-to-end anastomosis in the orthotopic model.
In both models, the development of obliterative lesions histological similar to clinical OAD has been demonstrated (1-7).
This video shows how to perform both, the heterotopic as well as the orthotopic tracheal transplantation technique in mice, and compares the time course of OAD development in both models using histology.

This video shows and compares two experimental models to study the development of obliterative airway disease (OAD) in mice, the heterotopic and orthotopic tracheal transplantation model.

Obliterative airway disease (OAD) is the major complication after lung transplantations that limits long term survival (1-7).
To study the ...

Isolation of Human Umbilical Arterial Smooth Muscle Cells (HUASMC)

The human umbilical cord (UC) is a biological sample that can be easily obtained just after birth. This biological sample is, most of the time, discarded and their collection does not imply any added risk to the newborn or mother s health. Moreover no ethical concerns are raised. The UC is composed by one vein and two arteries from which both endothelial cells (ECs) 1 and smooth muscle cells (SMCs) 2, two of the main cellular components of blood vessels, can be isolated. In this project the SMCs were obtained after enzymatic treatment of the UC arteries accordingly the experimental procedure previously described by Jaffe et al 3. After cell isolation they were kept in t-flash with DMEM-F12 supplemented with 5% of fetal bovine serum and were cultured for several passages. Cells maintained their morphological and other phenotypic characteristics in the different generations. The aim of this study was to isolate smooth muscle cells in order to use them as models for future assays with constrictor drugs, isolate and structurally characterize L-type calcium channels, to study cellular and molecular aspects of the vascular function 4 and to use them in tissue engineering.

Isolation of Human Umbilical Arterial Smooth Muscle Cells HUASMC

The umbilical cords are used to isolate smooth muscle cells by different ways. In this work we used the enzymatic treatment to isolated smooth muscle cells.

The human umbilical cord (UC) is a biological sample that can be easily obtained just after birth. This biological sample is, most of the time, discarded ...

Detection of Nitric Oxide and Superoxide Radical Anion by Electron Paramagnetic Resonance Spectroscopy from Cells using Spin Traps

Reactive nitrogen/oxygen species (ROS/RNS) at low concentrations play an important role in regulating cell function, signaling, and immune response but in unregulated concentrations are detrimental to cell viability1, 2. While living systems have evolved with endogenous and dietary antioxidant defense mechanisms to regulate ROS generation, ROS are produced continuously as natural by-products of normal metabolism of oxygen and can cause oxidative damage to biomolecules resulting in loss of protein function, DNA cleavage, or lipid peroxidation3, and ultimately to oxidative stress leading to cell injury or death4. 
Superoxide radical anion (O2&bull;-) is the major precursor of some of the most highly oxidizing species known to exist in biological systems such as peroxynitrite and hydroxyl radical. The generation of O2&bull;- signals the first sign of oxidative burst, and therefore, its detection and/or sequestration in biological systems is important. In this demonstration, O2&bull;- was generated from polymorphonuclear neutrophils (PMNs). Through chemotactic stimulation with phorbol-12-myristate-13-acetate (PMA), PMN generates O2&bull;- via activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase5. 
Nitric oxide (NO) synthase which comes in three isoforms, as inducible-, neuronal- and endothelial-NOS, or iNOS, nNOS or eNOS, respectively, catalyzes the conversion of L- arginine to L-citrulline, using NADPH to produce NO6. Here, we generated NO from endothelial cells. Under oxidative stress conditions, eNOS for example can switch from producing NO to O2&bull;- in a process called uncoupling, which is believed to be caused by oxidation of heme7 or the co-factor, tetrahydrobiopterin (BH4)8.
There are only few reliable methods for the detection of free radicals in biological systems but are limited by specificity and sensitivity. Spin trapping is commonly used for the identification of free radicals and involves the addition reaction of a radical to a spin trap forming a persistent spin adduct which can be detected by electron paramagnetic resonance (EPR) spectroscopy. The various radical adducts exhibit distinctive spectrum which can be used to identify the radicals being generated and can provide a wealth of information about the nature and kinetics of radical production9.
The cyclic nitrones, 5,5-dimethyl-pyrroline-N-oxide, DMPO10, the phosphoryl-substituted DEPMPO11, and the ester-substituted, EMPO12 and BMPO13, have been widely employed as spin traps--the latter spin traps exhibiting longer half-lives for O2&bull;- adduct. Iron (II)-N-methyl-D-glucamine dithiocarbamate, Fe(MGD)2 is commonly used to trap NO due to high rate of adduct formation and the high stability of the spin adduct14.

Electron paramagnetic resonance (EPR) spectroscopy was employed to detect nitric oxide from bovine aortic endothelial cells and superoxide radical anion from human neutrophils using iron (II)-N-methyl-D-glucamine dithiocarbamate, Fe(MGD)2 and 5,5-dimethyl-1-pyroroline-N-oxide, DMPO, respectively.

Reactive nitrogen/oxygen species (ROS/RNS) at low concentrations play an important role in regulating cell function, signaling, and immune response but in ...

Procedures for Rat in situ Skeletal Muscle Contractile Properties

There are many circumstances where it is desirable to obtain the contractile response of skeletal muscle under physiological circumstances: normal circulation, intact whole muscle, at body temperature. This includes the study of contractile responses like posttetanic potentiation, staircase and fatigue. Furthermore, the consequences of disease, disuse, injury, training and drug treatment can be of interest. This video demonstrates appropriate procedures to set up and use this valuable muscle preparation.
To set up this preparation, the animal must be anesthetized, and the medial gastrocnemius muscle is surgically isolated, with the origin intact. Care must be taken to maintain the blood and nerve supplies. A long section of the sciatic nerve is cleared of connective tissue, and severed proximally. All branches of the distal stump that do not innervate the medial gastrocnemius muscle are severed. The distal nerve stump is inserted into a cuff lined with stainless steel stimulating wires. The calcaneus is severed, leaving a small piece of bone still attached to the Achilles tendon. Sonometric crystals and/or electrodes for electromyography can be inserted. Immobilization by metal probes in the femur and tibia prevents movement of the muscle origin. The Achilles tendon is attached to the force transducer and the loosened skin is pulled up at the sides to form a container that is filled with warmed paraffin oil. The oil distributes heat evenly and minimizes evaporative heat loss. A heat lamp is directed on the muscle, and the muscle and rat are allowed to warm up to 37&deg;C. While it is warming, maximal voltage and optimal length can be determined. These are important initial conditions for any experiment on intact whole muscle. The experiment may include determination of standard contractile properties, like the force-frequency relationship, force-length relationship, and force-velocity relationship.
With care in surgical isolation, immobilization of the origin of the muscle and alignment of the muscle-tendon unit with the force transducer, and proper data analysis, high quality measurements can be obtained with this muscle preparation.

Procedures for Rat in situ Skeletal Muscle Contractile Properties

This video demonstrates the surgical preparation and procedures needed to study the contractile responses of the rat medial gastrocnemius muscle preparation in situ. This preparation allows measurement of skeletal muscle contractile properties under physiological conditions. The animal is anesthetized and the muscle is separated from surrounding tissue at its distal end. The Achilles tendon is attached to a force transducer, allowing measurement of the muscle&#x2019;s contractile response at 37 degrees C with an intact circulation.

There are many circumstances where it is desirable to obtain the contractile response of skeletal muscle under physiological circumstances: normal ...

Exploring Arterial Smooth Muscle Kv7 Potassium Channel Function using Patch Clamp Electrophysiology and Pressure Myography

Contraction or relaxation of smooth muscle cells within the walls of resistance arteries determines the artery diameter and thereby controls flow of blood through the vessel and contributes to systemic blood pressure. The contraction process is regulated primarily by cytosolic calcium concentration ([Ca2+]cyt), which is in turn controlled by a variety of ion transporters and channels. Ion channels are common intermediates in signal transduction pathways activated by vasoactive hormones to effect vasoconstriction or vasodilation. And ion channels are often targeted by therapeutic agents either intentionally (e.g. calcium channel blockers used to induce vasodilation and lower blood pressure) or unintentionally (e.g. to induce unwanted cardiovascular side effects).
Kv7 (KCNQ) voltage-activated potassium channels have recently been implicated as important physiological and therapeutic targets for regulation of smooth muscle contraction. To elucidate the specific roles of Kv7 channels in both physiological signal transduction and in the actions of therapeutic agents, we need to study how their activity is modulated at the cellular level as well as evaluate their contribution in the context of the intact artery.
The rat mesenteric arteries provide a useful model system. The arteries can be easily dissected, cleaned of connective tissue, and used to prepare isolated arterial myocytes for patch clamp electrophysiology, or cannulated and pressurized for measurements of vasoconstrictor/vasodilator responses under relatively physiological conditions. Here we describe the methods used for both types of measurements and provide some examples of how the experimental design can be integrated to provide a clearer understanding of the roles of these ion channels in the regulation of vascular tone.

Measurements of Kv7 (KCNQ) potassium channel activity in isolated arterial myocytes (using patch clamp electrophysiological techniques) in parallel with measurements of constrictor/dilator responses (using pressure myography) can reveal important information about the roles of Kv7 channels in vascular smooth muscle physiology and pharmacology.

Contraction  or relaxation of smooth muscle cells within the walls of resistance arteries  determines the artery diameter and thereby controls flow of ...

Assessment of Calcium Sparks in Intact Skeletal Muscle Fibers

Maintaining homeostatic Ca2+ signaling is a fundamental physiological process in living cells. Ca2+ sparks are the elementary units of Ca2+ signaling in the striated muscle fibers that appear as highly localized Ca2+ release events mediated by ryanodine receptor (RyR) Ca2+ release channels on the sarcoplasmic reticulum (SR) membrane. Proper assessment of muscle Ca2+ sparks could provide information on the intracellular Ca2+&#160;handling properties of healthy and diseased striated muscles. Although Ca2+ sparks events are commonly seen in resting cardiomyocytes, they are rarely observed in resting skeletal muscle fibers; thus there is a need for methods to generate and analyze sparks in skeletal muscle fibers.
Detailed here is an experimental protocol for measuring Ca2+ sparks in isolated flexor digitorm brevis (FDB) muscle fibers using fluorescent Ca2+ indictors and laser scanning confocal microscopy. In this approach, isolated FDB fibers are exposed to transient hypoosmotic stress followed by a return to isotonic physiological solution. Under these conditions, a robust Ca2+ sparks response is detected adjacent to the sarcolemmal membrane in young healthy FDB muscle fibers. Altered Ca2+ sparks response is detected in dystrophic or aged skeletal muscle fibers. This approach has recently demonstrated that membrane-delimited signaling involving cross-talk between inositol (1,4,5)-triphosphate receptor (IP3R) and RyR contributes to Ca2+ spark activation in skeletal muscle. In summary, our studies using osmotic stress induced Ca2+ sparks showed that this intracellular response reflects a muscle signaling mechanism in physiology and aging/disease states, including mouse models of muscle dystrophy (mdx mice) or amyotrophic lateral sclerosis (ALS model).

Described here is a method to directly measure calcium sparks, the elementary units of Ca2+ release from sarcoplasmic reticulum&#160;in intact skeletal muscle fibers. This method utilizes osmotic-stress-mediated triggering of Ca2+ release from ryanodine receptor in isolated muscle fibers. The dynamics and homeostatic capacity of intracellular Ca2+ signaling can be employed to assess muscle function in health and disease.

Maintaining homeostatic Ca2+ signaling is a fundamental physiological process in living cells. Ca2+ sparks are the elementary units of Ca2+ signaling in ...

Measurement of Smooth Muscle Function in the Isolated Tissue Bath-applications to Pharmacology Research

Isolated tissue bath assays are a classical pharmacological tool for evaluating concentration-response relationships in a myriad of contractile tissues. While this technique has been implemented for over 100 years, the versatility, simplicity and reproducibility of this assay helps it to remain an indispensable tool for pharmacologists and physiologists alike. Tissue bath systems are available in a wide array of shapes and sizes, allowing a scientist to evaluate samples as small as murine mesenteric arteries and as large as porcine ileum &#8211; if not larger. Central to the isolated tissue bath assay is the ability to measure concentration-dependent changes to isometric contraction, and how the efficacy and potency of contractile agonists can be manipulated by increasing concentrations of antagonists or inhibitors. Even though the general principles remain relatively similar, recent technological advances allow even more versatility to the tissue bath assay by incorporating computer-based data recording and analysis software. This video will demonstrate the function of the isolated tissue bath to measure the isometric contraction of an isolated smooth muscle (in this case rat thoracic aorta rings), and share the types of knowledge that can be created with this technique. Included are detailed descriptions of aortic tissue dissection and preparation, placement of aortic rings in the tissue bath and proper tissue equilibration prior to experimentation, tests of tissue viability, experimental design and implementation, and data quantitation. Aorta will be connected to isometric force transducers, the data from which will be captured using a commercially available analog-to-digital converter and bridge amplifier specifically designed for use in these experiments. The accompanying software to this system will be used to visualize the experiment and analyze captured data.

This protocol describes the measurement of isometric contraction in an isolated smooth muscle preparation, using an isolated tissue bath system and computer-based data acquisition.

Isolated tissue bath assays are a classical pharmacological tool for evaluating concentration-response relationships in a myriad of contractile tissues.  ...