Name: standardized rat coronary ring preparation and real-time recording of dynamic tension changes along vessel diameter
Uploaded: 2022-06-16T14:50:00
Description: Watch this Scientific Journal Video about Standardized Rat Coronary Ring Preparation and Real-Time Recording of Dynamic Tension Changes Along Vessel Diameter at JoVE.com

This work was supported by the Key R&#38;D project of Sichuan Provincial Science and Technology Plan (2022YFS0438), the National Natural Science Foundation of China (82104533), the China Postdoctoral Science Foundation (2020M683273), and the Science &#38; Technology Department of Sichuan Province (2021YJ0175).

The animal protocol was reviewed and approved by the Management Committee from Chengdu University of Traditional Chinese Medicine (Record No. 2021-11). Male Sprague Dawley (SD) rats (260-300 g, 8-10 weeks old) were used for the present study. The rats were kept in an animal chamber and were free to drink and eat during the experiment.
1. Solution preparation
<ol>
	<li>Prepare physiological salt solution (PSS) by dissolving 118 mM of NaCl, 4.7 mM of K+, 2.5 mM of C...

<ol>
	<li>Malakar, A. 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=A+review+on+coronary+artery+disease,+its+risk+factors,+and+therapeutics.">A review on coronary artery disease, its risk factors, and therapeutics.</a> Journal of Cellular Physiology. 234 (10), 16812-16823 (2019).</li><li>Murray, C., 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=national+age-sex+specific+all-cause+and+cause-specific+mortality+for+240+causes+of+death,+1990-2013:+A+systematic+analysis+for+the+global+burden+of+disease+Study+2013.">national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: A systematic analysis for the global burden of disease Study 2013.</a> The Lancet. 385 (9963), 117-171 (2015).</li><li>Zhang, 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=Adenosine+and+adenosine+receptor-mediated+action+in+coronary+microcirculation.">Adenosine and adenosine receptor-mediated action in coronary microcirculation.</a> Basic Research in Cardiology. 116 (1), 22 (2021).</li><li>Allaqaband, H., Gutterman, D. D., Kadlec, A. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiological+consequences+of+coronary+arteriolar+dysfunction+and+its+influence+on+cardiovascular+disease.">Physiological consequences of coronary arteriolar dysfunction and its influence on cardiovascular disease.</a> Physiology. 33 (5), 338-347 (2018).</li><li>Minelli, S., Minelli, P., Montinari, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reflections+on+atherosclerosis:+Lesson+from+the+past+and+future+research+directions.">Reflections on atherosclerosis: Lesson from the past and future research directions.</a> Journal of Multidisciplinary Healthcare. 13, 621-633 (2020).</li><li>Alvarez-Alvarez, M. M., Zanetti, D., Carreras-Torres, R., Moral, P., Athanasiadis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+survey+of+sub-saharan+gene+flow+into+the+mediterranean+at+risk+loci+for+coronary+artery+disease.">A survey of sub-saharan gene flow into the mediterranean at risk loci for coronary artery disease.</a> European Journal of Human Genetics. 25 (4), 472-476 (2017).</li><li>LaCombe, P., Tariq, M. A., Lappin, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiology,+Afterload+Reduction.">Physiology, Afterload Reduction.</a> StatPearls [Internet]. , (2022).</li><li>Gutterman, D. D., 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=The+human+microcirculation:+regulation+of+flow+and+beyond.">The human microcirculation: regulation of flow and beyond.</a> Circulation Research. 118 (1), 157-172 (2016).</li><li>Wang, G., Li, F., Hou, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complementary+and+alternative+therapies+for+stable+angina+pectoris+of+coronary+heart+disease:+A+protocol+for+systematic+review+and+network+meta-analysis.">Complementary and alternative therapies for stable angina pectoris of coronary heart disease: A protocol for systematic review and network meta-analysis.</a> Medicine. 101 (7), 28850 (2022).</li><li>Markousis-Mavrogenis, 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=Coronary+microvascular+disease:+the+&amp;#34;meeting+point&amp;#34;+of+cardiology.">Coronary microvascular disease: the &amp;#34;meeting point&amp;#34; of cardiology.</a> European Journal of Clinical Investigation. 52 (5), 13737 (2021).</li><li>Allison, B. 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=Fetal+in+vivo+continuous+cardiovascular+function+during+chronic+hypoxia.">Fetal in vivo continuous cardiovascular function during chronic hypoxia.</a> The Journal of Physiology. 594 (5), 1247-1264 (2016).</li><li>Wenceslau, C. 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=Guidelines+for+the+measurement+of+vascular+function+and+structure+in+isolated+arteries+and+veins.">Guidelines for the measurement of vascular function and structure in isolated arteries and veins.</a> American Journal of Physiology-Heart and Circulatory Physiology. 321 (1), 77-111 (2021).</li><li>Liu, 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=Comparison+of+Ca2++handling+for+the+regulation+of+vasoconstriction+between+rat+coronary+and+renal+arteries.">Comparison of Ca2+ handling for the regulation of vasoconstriction between rat coronary and renal arteries.</a> Journal of Vascular Research. 56 (4), 191-203 (2019).</li><li>Sun, 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=Isometric+contractility+measurement+of+the+mouse+mesenteric+artery+using+wire+myography.">Isometric contractility measurement of the mouse mesenteric artery using wire myography.</a> Journal of Visualized Experiments. (138), e58064 (2018).</li><li>Guo, 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=Coronary+hypercontractility+to+acidosis+owes+to+the+greater+activity+of+TMEM16A/ANO1+in+the+arterial+smooth+muscle+cells.">Coronary hypercontractility to acidosis owes to the greater activity of TMEM16A/ANO1 in the arterial smooth muscle cells.</a> Biomedicine &amp; Pharmacotherapy. 139, 111615 (2021).</li><li>Ping, N. N., Cao, L., Xiao, X., Li, S., Cao, Y. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+determination+of+optimal+initial+tension+in+rat+coronary+artery+using+wire+myography.">The determination of optimal initial tension in rat coronary artery using wire myography.</a> Physiological Research. 63 (1), 143-146 (2014).</li><li>Niccoli, G., Scalone, G., Lerman, A., Crea, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+microvascular+obstruction+in+acute+myocardial+infarction.">Coronary microvascular obstruction in acute myocardial infarction.</a> European Heart Journal. 37 (13), 1024-1033 (2016).</li><li>Mumma, B., Flacke, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+diagnostic+and+therapeutic+strategies+in+microvascular+angina.">Current diagnostic and therapeutic strategies in microvascular angina.</a> Current Emergency and Hospital Medicine Reports. 3 (1), 30-37 (2015).</li><li>Lanza, G. A., Parrinello, R., Figliozzi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Management+of+microvascular+angina+pectoris.">Management of microvascular angina pectoris.</a> American Journal of Cardiovascular Drugs. 14 (1), 31-40 (2014).</li><li>Zhu, T. Q., 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=Beneficial+effects+of+intracoronary+tirofiban+bolus+administration+following+upstream+intravenous+treatment+in+patients+with+ST-elevation+myocardial+infarction+undergoing+primary+percutaneous+coronary+intervention:+The+ICT-AMI+study.">Beneficial effects of intracoronary tirofiban bolus administration following upstream intravenous treatment in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention: The ICT-AMI study.</a> International Journal of Cardiology. 165 (3), 437-443 (2013).</li><li>Huang, D., 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=Restoration+of+coronary+flow+in+patients+with+no-reflow+after+primary+coronary+intervention+of+acute+myocardial+infarction+(RECOVER).">Restoration of coronary flow in patients with no-reflow after primary coronary intervention of acute myocardial infarction (RECOVER).</a> American Heart Journal. 164 (3), 394-401 (2012).</li><li>Fu, W. 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=Anti-atherosclerosis+and+cardio-protective+effects+of+the+Angong+Niuhuang+Pill+on+a+high+fat+and+vitamin+D3+induced+rodent+model+of+atherosclerosis.">Anti-atherosclerosis and cardio-protective effects of the Angong Niuhuang Pill on a high fat and vitamin D3 induced rodent model of atherosclerosis.</a> Journal of Ethnopharmacology. 195, 118-126 (2017).</li><li>Li, 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=Chinese+medicine+She-Xiang-Xin-Tong-Ning,+containing+moschus,+corydalis+and+ginseng,+protects+from+myocardial+ischemia+injury+via+angiogenesis.">Chinese medicine She-Xiang-Xin-Tong-Ning, containing moschus, corydalis and ginseng, protects from myocardial ischemia injury via angiogenesis.</a> The American Journal of Chinese Medicine. 48 (1), 107-126 (2020).</li><li>Wu, W., 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=Three+dimensional+reconstruction+of+coronary+artery+stents+from+optical+coherence+tomography:+Experimental+validation+and+clinical+feasibility.">Three dimensional reconstruction of coronary artery stents from optical coherence tomography: Experimental validation and clinical feasibility.</a> Scientific Reports. 11 (1), 1-15 (2021).</li><li>Liu, 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=Janus-like+role+of+fibroblast+growth+factor+2+in+arteriosclerotic+coronary+artery+disease:+Atherogenesis+and+angiogenesis.">Janus-like role of fibroblast growth factor 2 in arteriosclerotic coronary artery disease: Atherogenesis and angiogenesis.</a> Atherosclerosis. 229 (1), 10-17 (2013).</li><li>Hu, G., Li, X., Zhang, S., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Association+of+rat+thoracic+aorta+dilatation+by+astragaloside+IV+with+the+generation+of+endothelium-derived+hyperpolarizing+factors+and+nitric+oxide,+and+the+blockade+of+Ca2++channels.">Association of rat thoracic aorta dilatation by astragaloside IV with the generation of endothelium-derived hyperpolarizing factors and nitric oxide, and the blockade of Ca2+ channels.</a> Biomedical reports. 5 (1), 27-34 (2016).</li><li>Guo, 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=Anticonstriction+effect+of+MCA+in+rats+by+danggui+buxue+decoction.">Anticonstriction effect of MCA in rats by danggui buxue decoction.</a> Frontiers in Pharmacology. 12, 749915 (2021).</li><li>Jing, 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=Apigenin+relaxes+rat+intrarenal+arteries,+depresses+Ca2+-activated+Cl&#8722;+currents+and+augments+voltage-dependent+K++currents+of+the+arterial+smooth+muscle+cells.">Apigenin relaxes rat intrarenal arteries, depresses Ca2+-activated Cl&#8722; currents and augments voltage-dependent K+ currents of the arterial smooth muscle cells.</a> Biomedicine &amp; Pharmacotherapy. 115, 108926 (2019).</li></ol>

The disturbance of coronary microcirculation, which involves a wide range of patients with CAD, has been gradually recognized and concerned the basis for adequate myocardium perfusion. Considering the serious complications of sudden coronary heart disease and cardiovascular disease, timely drug prevention and treatment are extremely important for a clinical individual with CAD17. Inevitably, the secrecy of coronary artery anatomy and the complexity of its physiological structure have severely rest...

Coronary artery disease (CAD) has been widely recognized and concerned as a typical and representative cardiovascular disease, being the leading cause of death in both developed and developing countries1,2. As a blood and oxygen supply route for normal cardiac physiological function, circulating blood enters and nourishes the heart through two main coronary arteries and a blood vascular network on the surface of the myocardium3,4. Cholesterol and fat deposits in the coronary arteries cut off the heart&#39;s blood supply and the violent inflammatory response of the vascular system, causing atherosclerosis, stable angina, unstable angina, myocardial infarction, or sudden cardiac death5,6. In response to pathological stenosis of the coronary arteries, compensatory accelerated physiological heartbeat satisfies the blood supply of the heart itself or vital organs of the body by increasing the output of the left ventricle7. If prolonged coronary stenosis is not relieved in time, extensive new blood vessels may develop in certain areas of the heart8. At present, the clinical treatment of CAD often adopts drug thrombolysis or surgical mechanical thrombolysis and an exogenous bionic vascular bypass with frequent medication and great surgical disability9. Therefore, the functional investigation of coronary artery physiological activity is still an urgent breakthrough for cardiovascular diseases10.
There are no available technical means to detect coronary physiological activity, except for wireless telemetry systems, which can dynamically record in vivo coronary pressure, vascular tension, blood oxygen saturation, and pH values11. Therefore, considering coronary arteries&#39; textural secrecy and complexity, accurate identification and isolation of coronary arteries are undoubtedly the best choices for exploring multiple mechanisms of CAD in vitro4.
A series multi myograph system, in particular a wire micrograph microvascular tension detector (see Table of Materials), is a very mature marketable device for recording in vitro tissue tension changes of small vascular, lymphatic, and bronchial tubes with the characteristics of high precision and continuous dynamic recording12. The said system has been extensively employed to record in vitro tissue tension characteristics of cavity structures with diameters of 60 &#181;m to 10 mm. The continuous heating features of the platform of the wire micrograph largely offset the stimulation of the adverse external environment. Meanwhile, the constant inputs of the gas mixture and the pH values allow us to obtain more accurate vascular tension data in a similar physiological state13. However, considering the complexity of anatomical localization of rat coronary arteries (Figure 1), its isolation has been perplexing and limiting the mechanism&#39;s exploration of diversified cardiovascular disease and drug development. Therefore, the present protocol introduces the anatomical location and separation process of the rat coronary artery in detail, followed by tension measurement on the platform of the wire micrograph14.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Apigenin</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>150731</td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A501330</td>
			<td></td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A610219</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Xiya Reagent Co., Ltd., Shandong, China</td>
			<td>S3872</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A100395</td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A100781</td>
			<td></td>
		</tr>
		<tr>
			<td>LabChart Professional version 8.3&#160;</td>
			<td>ADInstruments, Australia</td>
			<td>&#8212;</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2&#183;6H2O</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A100288</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi myograph system&#160;</td>
			<td>Danish Myo Technology, Aarhus, Denmark</td>
			<td>620M</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A100241</td>
			<td></td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Sangon Biotech Co., Ltd., Shanghai, China</td>
			<td>A100865</td>
			<td></td>
		</tr>
		<tr>
			<td>Steel wires</td>
			<td>Danish Myo Technology, Aarhus, Denmark</td>
			<td>400447</td>
			<td></td>
		</tr>
		<tr>
			<td>U46619</td>
			<td>Sigma, USA</td>
			<td>D8174</td>
			<td></td>
		</tr>
	</tbody>
</table>

standardized rat coronary ring preparation and real-time recording of dynamic tension changes along vessel diameter

As a key event of cardiovascular system diseases, coronary artery disease (CAD) has been widely regarded as the main culprit of atherosclerosis, myocardial infarction, and angina pectoris, which seriously threaten the life and health of people all over the world. However, how to record the dynamic biomechanical characteristics of isolated blood vessels has long puzzled people. Meanwhile, precise positioning and isolation of coronary arteries to measure in vitro dynamic vascular tension changes have become a trend in CAD drug development. The present protocol describes the macroscopic identification and microscopic separation of rat coronary arteries. The contraction and dilation function of the coronary artery ring along the vessel diameter was monitored using the established multi myograph system. The standardized and programmed protocols of coronary ring tension measurement, from sampling to data acquisition, tremendously improve the repeatability of the experimental data, which ensures the authenticity of vascular tension records after physiological, pathological, and drug intervention.

Anatomically positioned, rat coronary arteries distributed and hidden deep in myocardial tissue were not easily recognized. By comparing the coronary arteries of humans (Figure 1A) and rats (Figure 1B), rapid and accurate separation of rat coronary arteries was conducted according to the sampling process in Figure 2. After precisely locating the right auricle, pulmonary artery, and apex from the front under an optical microscope, th...

Watch this Scientific Journal Video about Standardized Rat Coronary Ring Preparation and Real-Time Recording of Dynamic Tension Changes Along Vessel Diameter at JoVE.com

Standardized Rat Coronary Ring Preparation and Real-Time Recording of Dynamic Tension Changes Along Vessel Diameter

The present protocol describes the wire myograph technique for measuring vascular reactivity of the rat coronary artery.

As a key event of cardiovascular system diseases, coronary artery disease (CAD) has been widely regarded as the main culprit of atherosclerosis, ...

This protocol introduces in detail the localization, separation, and the muscular ring fixation of rat coronary arteries. Providing a new method for the mechanisms, exploration, and the treatment of various cardiovascular diseases. The system is suitable for and the stable recording of the dynamic changes of in vitro arterial tension, reading in diameter from 60 micrometers to 10 millimeters.We suggest that novices should first accurately understand the anatomical location of each vessel and can start with slightly larger vessel such as the thoracic artery and the mesenteric artery. After dissociating and removing the heart, begin by draining the residual blood from all the heart chambers by mildly squeezing with medical plastic forceps. Quickly place the pre-processed heart in a Petri dish containing 95%oxygen and 5%carbon dioxide saturated physiological salt solution at four degrees Celsius, having a pH value of 7.40.To accurately identify the anatomical position of the coronary arteries, adjust the posture of the isolated heart under the light microscope according to the schematic diagram. Cut the left and right ventricular cavities along the inter ventricular septum from the root of the pulmonary artery with surgical scissors and tweezers. To dissociate the left and right coronary arteries from the myocardial tissue, dissect the right ventricle under an optical anatomic microscope to thoroughly expose the right coronary artery branch.Then identify the position of the left coronary artery by rotating the heart tissue 45 degrees clockwise. After removing the surrounding sticky myocardial tissue, explicitly discern the pulsing left and right coronary arteries. Separate the coronary arteries in the middle immediately and completely immerse in physiological salt solution at four degree Celsius.Acquire an arterial ring of about two millimeters by vertically cutting the detached artery with anatomical scissors to record the vascular tension under different stimuli. Prepare two two centimeter stainless steel wires and pre-soak in four degree Celsius physiological salt solution saturated with 95%oxygen and 5%carbon dioxide. Pass both the wires parallelly through the arterial ring along with the vessel's direction under an optical anatomical microscope and with wires of equal length exposed at both ends of the vascular cavity.Fix the arterial ring with the steel wire front and back in the bath of the wire micrograph filled with bubbling physiological salt solution with 95%oxygen and 5%carbon dioxide. Rotate the horizontal screw knob for an appropriate front and rear spacing so that the two wires are horizontal and the arterial ring is in a natural state of relaxation. After installing the DMT bath on the thermostatic apparatus, open the data acquisition software to ensure that the corresponding path signal was recorded.Set the parameters. Achieve the optimal initial tension of the arterial ring by applying a reasonable tension along the diameter of the vessel. At this point, set the displayed vascular tension value to zero.Afterward, apply a three milli Newton pulse stimulus to the arterial ring by rotating the spiral axis of the bath. Click the LCD panel to set it to zero milli Newton and maintain for one hour. After incubation for one hour in oxygen saturated physiological salt solution buffer at 37 degree Celsius pH 7.40, set the tension value to zero milli Newton again on the tension control panel of the wire micrograph.Perform the contractile activity of the coronary artery ring with the wire myograph technique and validate in three separate operations by stimulating with 60 millimolar of potassium ion solution for 10 minutes each. After each stimulation, flush the bath with the oxygen saturated physiological salt solution until vascular tone returns to its initial state. Add 0.3 micromolar U46619 to bath and observe for 10 minutes.Add one micromolar apigenin and observe vascular effects. When dilation reaches a plateau, add the next concentration. Add one micromolar apigenin to 60 millimolar potassium pre-shrinking solution to observe the vascular effect.When dilation reaches a plateau, add the next concentration. Add 28 millimolar potassium ion to the resting vascular ring. When the contraction reaches a plateau, add the next concentration.Add 0.01 micromolar U46619 to the resting vascular ring. When the contraction reaches a plateau, add the next concentration. After an initial three milli Newton tension was applied to the arterial ring, its tension exceeded more than two milli Newton by applying 60 millimolar potassium ion concentration in parallel three times.Thus the procedures above had resulted in an isolated coronary ring with excellent physiological activity. Cumulative potassium ion concentration, or U46619 were added to the bath of DMT620M, resulting in a concentration dependent increase in vitro vascular tone. The next concentration of potassium ion or U46619 was added when the vasoconstriction effect reached a plateau.For isolated coronary rings constricted by potassium ion and U46619, the test drug apigenin in caused vasodilation in a surprisingly concentration dependent manner. The heart is dissected along the ventricular septum from the root of the pulmonary artery, exposing and separating two millimeters coronary muscular ring. Following this procedure, we can record vascular tension in retinal microvessels, renal function, renal artery, and in the middle cerebral artery.A region dynamic from 60 micrometers to 10 millimeters.

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X-ray Dose Reduction through Adaptive Exposure in Fluoroscopic Imaging

X-ray fluoroscopy is widely used for image guidance during cardiac intervention. However, radiation dose in these procedures can be high, and this is a significant concern, particularly in pediatric applications. Pediatrics procedures are in general much more complex than those performed on adults and thus are on average four to eight times longer1. Furthermore, children can undergo up to 10 fluoroscopic procedures by the age of 10, and have been shown to have a three-fold higher risk of developing fatal cancer throughout their life than the general population2,3.
We have shown that radiation dose can be significantly reduced in adult cardiac procedures by using our scanning beam digital x-ray (SBDX) system4-- a fluoroscopic imaging system that employs an inverse imaging geometry5,6 (Figure 1, Movie 1 and Figure 2). Instead of a single focal spot and an extended detector as used in conventional systems, our approach utilizes an extended X-ray source with multiple focal spots focused on a small detector. Our X-ray source consists of a scanning electron beam sequentially illuminating up to 9,000 focal spot positions. Each focal spot projects a small portion of the imaging volume onto the detector. In contrast to a conventional system where the final image is directly projected onto the detector, the SBDX uses a dedicated algorithm to reconstruct the final image from the 9,000 detector images.
For pediatric applications, dose savings with the SBDX system are expected to be smaller than in adult procedures. However, the SBDX system allows for additional dose savings by implementing an electronic adaptive exposure technique. Key to this method is the multi-beam scanning technique of the SBDX system: rather than exposing every part of the image with the same radiation dose, we can dynamically vary the exposure depending on the opacity of the region exposed. Therefore, we can significantly reduce exposure in radiolucent areas and maintain exposure in more opaque regions. In our current implementation, the adaptive exposure requires user interaction (Figure 3). However, in the future, the adaptive exposure will be real time and fully automatic.
We have performed experiments with an anthropomorphic phantom and compared measured radiation dose with and without adaptive exposure using a dose area product (DAP) meter. In the experiment presented here, we find a dose reduction of 30%.

We are developing a dynamic adaptive exposure technique using our scanning beam digital X-ray system. Rather than exposing an object uniformly, the exposure is adapted depending on the opacity of the object. Here we show an experiment on an anthropomorphic phantom that resulted in a dose saving of 30%.

X-ray fluoroscopy is widely used for image guidance during cardiac intervention. However, radiation dose in these procedures can be high, and this is a ...

Real-time Digital Imaging of Leukocyte-endothelial Interaction in Ischemia-reperfusion Injury (IRI) of the Rat Cremaster Muscle

Ischemia-reperfusion injury (IRI) has been implicated in a large array of pathological conditions such as cerebral stroke, myocardial infarction, intestinal ischemia as well as following transplant and cardiovascular surgery.1 Reperfusion of previously ischemic tissue, while essential for the prevention of irreversible tissue injury, elicits excessive inflammation of the affected tissue. Adjacent to the production of reactive oxygen species, activation of the complement system and increased microvascular permeability, the activation of leukocytes is one of the principle actors in the pathological cascade of inflammatory tissue damage during reperfusion.2, 3 Leukocyte activation is a multistep process consisting of rolling, firm adhesion and transmigration and is mediated by a complex interaction between adhesion molecules in response to chemoattractants such as complement factors, chemokines, or platelet-activating factor.4
While leukocyte rolling in postcapillary venules is predominantly mediated by the interaction of selectins5 with their counter ligands, firm adhesion of leukocytes to the endothelium is selectin-controlled via binding to intercellular adhesion molecules (ICAM) and vascular cellular adhesion molecules (VCAM).6, 7 
Gold standard for the in vivo observation of leukocyte-endothelial interaction is the technique of intravital microscopy, first described in 1968.8
Though various models of IRI (ischemia-reperfusion injury) have been described for various organs, 9-12 only few are suitable for direct visualization of leukocyte recruitment in the microvascular bed on a high level of image quality.8 
We here promote the digital intravital epifluorescence microscopy of the postcapillary venule in the cremasteric microcirculation of the rat 13 as a convenient method to qualitatively and quantitatively analyze leukocyte recruitment for IRI-research in striated muscle tissue and provide a detailed manual for accomplishing the technique. We further illustrate common pitfalls and provide useful tips which should enable the reader to truly appreciate, and safely perform the method.
In a step by step protocol we depict how to get started with respiration controlled anesthesia under sufficient monitoring to keep the animal firmly anesthetized for longer periods of time. We then describe the cremasteric preparation as a thin flat sheet for outstanding optical resolution and provide a protocol for leukocyte imaging in IRI that has been well established in our laboratories.

Real-time Digital Imaging of Leukocyte-endothelial Interaction in Ischemia-reperfusion Injury IRI of the Rat Cremaster Muscle

Digital intravital epifluorescence microscopy of postcapillary venules in the cremasteric microcirculation is a convenient method to gain insights into leukocyte-endothelial interaction in vivo in ischemia-reperfusion injury (IRI) of striated muscle tissue. We here provide a detailed protocol to safely perform the technique and discuss its applications and limitations.

Ischemia-reperfusion injury (IRI) has been implicated in a large array of pathological conditions such as cerebral stroke, myocardial infarction, ...

2-Vessel Occlusion/Hypotension: A Rat Model of Global Brain Ischemia

Cardiac arrest followed by resuscitation often results in dramatic brain damage caused by ischemia and subsequent reperfusion of the brain. Global brain ischemia produces damage to specific brain regions shown to be highly sensitive to ischemia 1. Hippocampal neurons have higher sensitivity to ischemic insults compared to other cell populations, and specifically, the CA1 region of the hippocampus is particularly vulnerable to ischemia/reperfusion 2.
The design of therapeutic interventions, or study of mechanisms involved in cerebral damage, requires a model that produces damage similar to the clinical condition and in a reproducible manner. Bilateral carotid vessel occlusion with hypotension (2VOH) is a model that produces reversible forebrain ischemia, emulating the cerebral events that can occur during cardiac arrest and resuscitation. We describe a model modified from Smith et al. (1984) 2, as first presented in its current form in Sanderson, et al. (2008) 3, which produces reproducible injury to selectively vulnerable brain regions 3-6. The reliability of this model is dictated by precise control of systemic blood pressure during applied hypotension, the duration of ischemia, close temperature control, a specific anesthesia regimen, and diligent post-operative care. An 8-minute ischemic insult produces cell death of CA1 hippocampal neurons that progresses over the course of 6 to 24 hr of reperfusion, while less vulnerable brain regions are spared. This progressive cell death is easily quantified after 7-14 days of reperfusion, as a near complete loss of CA1 neurons is evident at this time.
In addition to this brain injury model, we present a method for CA1 damage quantification using a simple, yet thorough, methodology. Importantly, quantification can be accomplished using a simple camera-mounted microscope, and a free ImageJ (NIH) software plugin, obviating the need for cost-prohibitive stereology software programs and a motorized microscopic stage for damage assessment.

Bilateral carotid occlusion coupled with systemic hypotension produces global brain ischemia in the rat, resulting in damage to the hippocampus with reproducible severity. Animal subjects are impaired with predictable patterns of brain damage, they recover expediently, and mortality rates are comparatively low.

Cardiac arrest followed by resuscitation often results in dramatic brain damage caused by ischemia and subsequent reperfusion of the brain. Global brain ...

Movement Retraining using Real-time Feedback of Performance

Any modification of movement - especially movement patterns that have been honed over a number of years - requires re-organization of the neuromuscular patterns responsible for governing the movement performance. This motor learning can be enhanced through a number of methods that are utilized in research and clinical settings alike. In general, verbal feedback of performance in real-time or knowledge of results following movement is commonly used clinically as a preliminary means of instilling motor learning. Depending on patient preference and learning style, visual feedback (e.g. through use of a mirror or different types of video) or proprioceptive guidance utilizing therapist touch, are used to supplement verbal instructions from the therapist. Indeed, a combination of these forms of feedback is commonplace in the clinical setting to facilitate motor learning and optimize outcomes.
Laboratory-based, quantitative motion analysis has been a mainstay in research settings to provide accurate and objective analysis of a variety of movements in healthy and injured populations. While the actual mechanisms of capturing the movements may differ, all current motion analysis systems rely on the ability to track the movement of body segments and joints and to use established equations of motion to quantify key movement patterns. Due to limitations in acquisition and processing speed, analysis and description of the movements has traditionally occurred offline after completion of a given testing session.
This paper will highlight a new supplement to standard motion analysis techniques that relies on the near instantaneous assessment and quantification of movement patterns and the display of specific movement characteristics to the patient during a movement analysis session. As a result, this novel technique can provide a new method of feedback delivery that has advantages over currently used feedback methods.

Retraining abnormal movement patterns following injury or disease is a key component of physical rehabilitation. Recent advances in technology have permitted accurate assessment of movement during a variety of tasks, with near instantaneous quantification of results. This provides new opportunities for modification of faulty movement patterns in real time.

Any modification of movement - especially movement patterns that have been honed over a number of years - requires re-organization of the neuromuscular ...

Chemotherapy-induced Vascular Toxicity - Real-time In vivo Imaging of Vessel Impairment

Certain classes of chemotherapies may exert acute vascular changes that may progress into long-term conditions that may predispose the patient to an increased risk of vascular morbidity.&#160;Yet, albeit&#160;the mounting clinical evidence, there is a paucity of clear studies of vascular toxicity and therefore the etiology of a heterogeneous group of vascular/cardiovascular disorders remains to be elucidated. Moreover, the mechanism that may underlie vascular toxicity can completely differ from the principles of chemotherapy-induced cardiotoxicity, which is related to direct myocyte injury. We have established a real-time, in vivo molecular imaging platform&#160;to evaluate&#160;the potential&#160;acute&#160;vascular toxicity of anti-cancer therapies.
We have set up a platform of in vivo, high-resolution molecular imaging&#160;in mice,&#160;suitable for visualizing vasculature within confined organs and reference blood vessels within the same individuals whereas each individual serve as its own control. Blood vessel walls were impaired after doxorubicin administration, representing a unique mechanism of vascular toxicity that may be the early event in end-organ injury. Herein, the method of fibered confocal fluorescent microscopy (FCFM) based imaging is described, which provides an innovative mode to understand physiological phenomena at the cellular and sub-cellular levels in animal subjects.

Chemotherapy-induced Vascular Toxicity - Real-time In vivo Imaging of Vessel Impairment

We herein describe the method of fibered confocal fluorescent microscopy (FCFM) based imaging, which provides an innovative mode to understand physiological phenomena at the cellular and sub-cellular levels in animal subjects.

Certain classes of chemotherapies may exert acute vascular changes that may progress into long-term conditions that may predispose the patient to an ...

Real-time Cytotoxicity Assays in Human Whole Blood

A live cell-based whole blood cytotoxicity assay (WCA) that allows access to temporal information of the overall cell cytotoxicity is developed with high-throughput cell positioning technology. The targeted tumor cell populations are first preprogrammed to immobilization into an array format, and labeled with green fluorescent cytosolic dyes. Following the cell array formation, antibody drugs are added in combination with human whole blood. Propidium iodide (PI) is then added to assess cell death. The cell array is analyzed with an automatic imaging system. While cytosolic dye labels the targeted tumor cell populations, PI labels the dead tumor cell populations. Thus, the percentage of target cancer cell killing can be quantified by calculating the number of surviving targeted cells to the number of dead targeted cells. With this method, researchers are able to access time-dependent and dose-dependent cell cytotoxicity information. Remarkably, no hazardous radiochemicals are used. The WCA presented here has been tested with lymphoma, leukemia, and solid tumor cell lines. Therefore, WCA allows researchers to assess drug efficacy in a highly relevant ex&#160;vivo condition.

The whole blood cytotoxicity assay (WCA) is a cytotoxicity assay developed by incorporating high-throughput cell positioning technology with fluorescence microscopy and automated image processing. Here, we describe how lymphoma cells treated with an anti-CD20 antibody can be analyzed real-time in human whole blood to provide quantitative cellular cytotoxicity analysis.

A live cell-based whole blood cytotoxicity assay (WCA) that allows access to temporal information of the overall cell cytotoxicity is developed with ...

Cavernous Nerve Stimulation and Recording of Intracavernous Pressure in a Rat

The stimulation of the cavernous nerve (CN) and measurement of intracavernous pressure (ICP) have been used extensively to test and evaluate therapies for erectile dysfunction. However, the methods used vary between laboratories, and pitfalls still exist. The goal of this study was to describe a surgical technique that would provide a reliable and reproducible model. By exposing the ischiocavernosus muscle at its point of insertion on the ischial tuberosity, the penile crus could be cannulated with minimal dissection and injury to the structures involved in erectile function. Repeated stimulation of the CN, without the need for lifting and drying, was achieved by using a 125 &#181;m bipolar silver electrode and biocompatible silicon glue to isolate the electrode-nerve complex. This method prevents neuropraxia by reducing stretching and drying the nerve and provides complete isolation of the nerve, negating electrical leakage and preventing stimulation of alternative pathways.

This study describes a simplified surgical procedure and technique for performing cavernous nerve stimulation with the isolation of the nerve-electrode complex using silicone glue and intracavernous pressure measurement.

The stimulation of the cavernous nerve (CN) and measurement of intracavernous pressure (ICP) have been used extensively to test and evaluate therapies for ...

Real-time Pressure-volume Analysis of Acute Myocardial Infarction in Mice

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any potential therapeutic approach directed against acute left ventricular (LV) dysfunction. Current imaging modalities (e.g., echocardiography and magnetic resonance imaging) have several limitations since data on LV pressure cannot directly be measured. LV catheterization in mice undergoing coronary artery occlusion could serve as a novel method for a real-time evaluation of LV function.
At the beginning of the procedure, mice were anesthetized followed by endotracheal intubation. For LV catheterization, the right carotid artery was exposed via middle-neck incision. The catheter was introduced and placed into the LV cavity. Left thoracotomy was conducted and the left main coronary artery (LCA) was ligated. To induce reperfusion, the suture was released after 45 min. Pressure-volume data was recorded at all times.
Ligation of the LCA caused a decrease in LV systolic function as evidenced by a 30% reduction in stroke volume, LV ejection fraction (EF), and cardiac output. Maximum dP/dt as a parameter for LV contractility was also significantly reduced and diastolic function was severely impaired (minimum dP/dt -40%). Reperfusion over a period of 20 min did not lead to a complete recovery of LV function.
Real-time pressure-volume analysis served as a valid procedure for monitoring cardiac function during acute myocardial infarction in mice. Maintaining stable anesthesia and a standardized surgical approach was crucial to ensure valid results. As the early phase of acute myocardial infarction is critical for morbidity and mortality, the delineated method could be beneficial for preclinical evaluation of new strategies for cardioprotection.

Acute myocardial infarction in mice induces acute but incompletely characterized changes in left ventricular (LV) function. LV catheterization in mice undergoing coronary artery occlusion serves as a novel method for a real-time evaluation of LV function.

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any ...

Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

Neurophysiological monitoring is an important goal in the treatment of neurocritical patients, as it may prevent secondary damage and directly impact morbidity and mortality rates. However, there is currently a lack of suitable non-invasive, real-time technologies for continuous monitoring of cerebral physiology at the bedside. Diffuse optical techniques have been proposed as a potential tool for bedside measurements of cerebral blood flow and cerebral oxygenation in case of neurocritical patients. Diffuse optical spectroscopies have been previously explored to monitor patients in several clinical scenarios ranging from neonatal monitoring to cerebrovascular interventions in adults. However, the feasibility of the technique to aid clinicians by providing real-time information at the bedside remains largely unaddressed. Here, we report the translation of a diffuse optical system for continuous real-time monitoring of cerebral blood flow, cerebral oxygenation, and cerebral oxygen metabolism during intensive care. The real-time feature of the instrument could enable treatment strategies based on patient-specific cerebral physiology rather than relying on surrogate metrics, such as arterial blood pressure. By providing real-time information on the cerebral circulation at different time scales with relatively cheap and portable instrumentation, this approach may be especially useful in low-budget hospitals, in remote areas and for&#160;monitoring in open fields (e.g., defense and sports).

Presented here is a protocol for non-invasively monitoring cerebral hemodynamics of neurocritical patients in real-time and at the bedside using diffuse optics. Specifically, the proposed protocol uses a hybrid diffuse optical systems to detect and display real-time information on cerebral oxygenation, cerebral blood flow and cerebral metabolism.

Neurophysiological monitoring is an important goal in the treatment of neurocritical patients, as it may prevent secondary damage and directly impact ...

Real-Time Dynamic Navigation System for the Precise Quad-Zygomatic Implant Placement in a Patient with a Severely Atrophic Maxilla

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive bone augmentation and shorten the treatment cycle. However, there are risks associated with the placement of ZIs, such as penetration of the orbital cavity or infra-temporal fossa. Furthermore, the placement of multiple ZIs makes this surgery risky and more difficult to perform. Potential intraoperative complications are extremely dangerous and may cause irreparable losses. Here, we describe a practical, feasible, and reproducible protocol for a real-time surgical navigation system for precisely placing quad-zygomatic implants in the severely atrophic maxilla of patients with residual bone that does not meet the requirements of conventional implants. Hundreds of patients have received ZIs at our department based on this protocol. The clinical outcomes have been satisfactory, the intraoperative and postoperative complications have been low, and the accuracy indicated by infusion of the designed image and postoperative three-dimensional image has been high. This method should be utilized during the entire surgical procedure to ensure ZI placement safety.

Here, we present a protocol to achieve precise quad-zygomatic implant placement in patients with severely atrophic maxilla using a real-time dynamic navigation system.

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive ...