Name: isolation of mitochondria from mouse skeletal muscle for respirometric assays
Uploaded: 2022-02-10T14:45:00
Description: Watch this Scientific Journal Video about Isolation of Mitochondria from Mouse Skeletal Muscle for Respirometric Assays at JoVE.com

We wish to thank Juan J. Tena for the use of the homogenizer and the CABD Proteomics and Animal Husbandry facilities for technical support. This work was supported by the Spanish Ministry of Education, Culture and Sports through fellowship FPU16/03264 to J.D.H.C., the Association Fran&#231;aise contre les Myopathies (AFM) through fellowship grant #22450 to C.V.-G., an Institutional Grant MDM-2016-0687 (Maria de Maeztu Excellence Unit, Department of Gene Regulation and Morphogenesis at CABD) and BFU2017-83150-P to J.J.C. The Junta de Andaluc&#237;a grant P18-RT-4572, the FEDER Funding Program from the European Union, and Spanish Ministry of Science, Innovation and Universities grant RED2018-102576-T to P.N.

Mouse housing and tissue collection were performed using protocols approved by the Universidad Pablo de Olavide Ethics Committee (Sevilla, Spain; protocols 24/04/2018/056 and 12/03/2021/033) in accordance with Spanish Royal Decree 53/2013, European Directive 2010/63/EU, and other relevant guidelines.
1. Preparation of stocks, buffers, and reagents for the respiration assays
<ol>
	<li>Prepare the following stock solutions, which can be stored at the indicated temperature for ...

<ol>
	<li>Spinelli, J. B., Haigis, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+multifaceted+contributions+of+mitochondria+to+cellular+metabolism.">The multifaceted contributions of mitochondria to cellular metabolism.</a> Nature Cell Biology. 20 (7), 745-754 (2018).</li><li>Alberts, 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=The+mitochondrion.">The mitochondrion.</a> Molecular Biology of the Cell, 4th edition. , (2002).</li><li>Turunen, M., Olsson, J., Dallner, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolism+and+function+of+coenzyme+Q.">Metabolism and function of coenzyme Q.</a> Biochimica et Biophysica Acta. 1660 (1-2), 171-199 (2004).</li><li>Alc&#225;zar-Fabra, M., Trevisson, E., Brea-Calvo, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+syndromes+associated+with+coenzyme+Q10+deficiency.">Clinical syndromes associated with coenzyme Q10 deficiency.</a> Essays in Biochemistry. 62 (3), 377-398 (2018).</li><li>Banerjee, R., Purhonen, J., Kallij&#228;rvi, 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+mitochondrial+coenzyme+Q+junction+and+complex+III:+biochemistry+and+pathophysiology.">The mitochondrial coenzyme Q junction and complex III: biochemistry and pathophysiology.</a> The FEBS Journal. , (2021).</li><li>Gorman, G. 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=Mitochondrial+diseases.">Mitochondrial diseases.</a> Nature Reviews. Disease Primers. 2, 16080 (2016).</li><li>Villalba, J. M., Navas, P. <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+coenzyme+Q+biosynthesis+pathway+in+eukaryotes.">Regulation of coenzyme Q biosynthesis pathway in eukaryotes.</a> Free Radical Biology &amp; Medicine. 165, 312-323 (2021).</li><li>Li, Z., Graham, B. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+mitochondrial+oxygen+consumption+using+a+Clark+electrode.">Measurement of mitochondrial oxygen consumption using a Clark electrode.</a> Methods in Molecular Biology. 837, 63-72 (2012).</li><li>Rogers, G. 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=High+throughput+microplate+respiratory+measurements+using+minimal+quantities+of+isolated+mitochondria.">High throughput microplate respiratory measurements using minimal quantities of isolated mitochondria.</a> PloS One. 6 (7), 21746 (2011).</li><li>Pala, 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=Distinct+metabolic+states+govern+skeletal+muscle+stem+cell+fates+during+prenatal+and+postnatal+myogenesis.">Distinct metabolic states govern skeletal muscle stem cell fates during prenatal and postnatal myogenesis.</a> Journal of Cell Science. 131 (14), 212977 (2018).</li><li>Shintaku, 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=MyoD+regulates+skeletal+muscle+oxidative+metabolism+cooperatively+with+alternative+NF-&#312;B.">MyoD regulates skeletal muscle oxidative metabolism cooperatively with alternative NF-&#312;B.</a> Cell Reports. 17 (2), 514-526 (2016).</li><li>Li, 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=Development+of+a+high-throughput+method+for+real-time+assessment+of+cellular+metabolism+in+intact+long+skeletal+muscle+fibre+bundles.">Development of a high-throughput method for real-time assessment of cellular metabolism in intact long skeletal muscle fibre bundles.</a> The Journal of Physiology. 594 (24), 7197-7213 (2016).</li><li>Schuh, R. A., Jackson, K. C., Khairallah, R. J., Ward, C. W., Spangenburg, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+mitochondrial+respiration+in+intact+single+muscle+fibers.">Measuring mitochondrial respiration in intact single muscle fibers.</a> American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 302 (6), 712-719 (2012).</li><li>Rosenblatt, J. D., Lunt, A. I., Parry, D. J., Partridge, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+satellite+cells+from+living+single+muscle+fiber+explants.">Culturing satellite cells from living single muscle fiber explants.</a> In Vitro Cellular &amp; Developmental Biology. Animal. 31 (10), 773-779 (1995).</li><li>Keire, P., Shearer, A., Shefer, G., Yablonka-Reuveni, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+culture+of+skeletal+muscle+myofibers+as+a+means+to+analyze+satellite+cells.">Isolation and culture of skeletal muscle myofibers as a means to analyze satellite cells.</a> Methods in Molecular Biology. 946, 431-468 (2013).</li><li>Shintaku, J., Guttridge, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+aerobic+respiration+in+intact+skeletal+muscle+tissue+by+microplate-based+respirometry.">Analysis of aerobic respiration in intact skeletal muscle tissue by microplate-based respirometry.</a> Methods in Molecular Biology. 1460, 337-343 (2016).</li><li>Bharadwaj, M. 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=Preparation+and+respirometric+assessment+of+mitochondria+isolated+from+skeletal+muscle+tissue+obtained+by+percutaneous+needle+biopsy.">Preparation and respirometric assessment of mitochondria isolated from skeletal muscle tissue obtained by percutaneous needle biopsy.</a> Journal of Visualized Experiments: JoVE. (96), e52350 (2015).</li><li>Garcia-Cazarin, M. L., Snider, N. N., Andrade, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+isolation+from+skeletal+muscle.">Mitochondrial isolation from skeletal muscle.</a> Journal of Visualized Experiments: JoVE. (49), e2452 (2011).</li><li>Iuso, A., Repp, B., Biagosch, C., Terrile, C., Prokisch, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+mitochondrial+bioenergetics+in+isolated+mitochondria+from+various+mouse+tissues+using+Seahorse+XF96+analyzer.">Assessing mitochondrial bioenergetics in isolated mitochondria from various mouse tissues using Seahorse XF96 analyzer.</a> Methods in Molecular Biology. 1567, 217-230 (2017).</li><li>Divakaruni, A. S., Rogers, G. W., Murphy, A. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+mitochondrial+function+in+permeabilized+cells+using+the+Seahorse+XF+analyzer+or+a+Clark-type+oxygen+electrode.">Measuring mitochondrial function in permeabilized cells using the Seahorse XF analyzer or a Clark-type oxygen electrode.</a> Current Protocols in Toxicology. 60, 1-16 (2014).</li><li>Das, K. C., Muniyappa, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-dependent+mitochondrial+energy+dynamics+in+the+mice+heart:+role+of+superoxide+dismutase-2.">Age-dependent mitochondrial energy dynamics in the mice heart: role of superoxide dismutase-2.</a> Experimental Gerontology. 48 (9), 947-959 (2013).</li><li>Aw, W. C., Bajracharya, R., Towarnicki, S. G., Ballard, J. W. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+bioenergetic+functions+from+isolated+mitochondria+in+Drosophila+melanogaster.">Assessing bioenergetic functions from isolated mitochondria in Drosophila melanogaster.</a> Journal of Biological Methods. 3 (2), 42 (2016).</li><li>Sakamuri, S. S. V. 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=Measurement+of+respiratory+function+in+isolated+cardiac+mitochondria+using+Seahorse+XFe24+analyzer:+applications+for+aging+research.">Measurement of respiratory function in isolated cardiac mitochondria using Seahorse XFe24 analyzer: applications for aging research.</a> Gerontology. 40 (3), 347-356 (2018).</li><li>Boutagy, N. E., Pyne, E., Rogers, G. W., Ali, M., Hulver, M. W., Frisard, M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+mitochondria+from+minimal+quantities+of+mouse+skeletal+muscle+for+high+throughput+microplate+respiratory+measurements.">Isolation of mitochondria from minimal quantities of mouse skeletal muscle for high throughput microplate respiratory measurements.</a> Journal of Visualized Experiments: JoVE. (105), e53217 (2015).</li><li>Sperling, J. 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=Measuring+respiration+in+isolated+murine+brain+mitochondria:+implications+for+mechanistic+stroke+studies.">Measuring respiration in isolated murine brain mitochondria: implications for mechanistic stroke studies.</a> Neuromolecular Medicine. 21 (4), 493-504 (2019).</li><li>Boutagy, N. E., Rogers, G. W., Pyne, E. S., Ali, M. M., Hulver, M. 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All methods used to study mitochondrial respiration have their limitations; hence, it is crucial to select the method that best suits a specific experimental question. This work provides an updated and detailed protocol to isolate mitochondria from mouse skeletal muscle to perform different respiratory assays to investigate mitochondrial function. Indeed, the study of mitochondrial bioenergetics in isolated mitochondria using microplate-based technologies is valuable to study tissue-specific respiration in terms of repro...

Mitochondria are the primary metabolic organelles in the cell1. These specialized membrane-enclosed organelles use nutrient molecules to produce energy in the form of adenosine triphosphate (ATP) by OXPHOS. This process relies on the transfer of electrons from donor molecules in a series of redox reactions in the ETC2. CoQ is the only redox-active lipid that is endogenously produced in all cellular membranes and circulating lipoproteins that shows antioxidant function3. It is an essential component of the ETC, transferring electrons from NADH-dependent complex I and FADH2-dependent complex II to complex III, although many other reductases can drive the reduction of mitochondrial CoQ to ubiquinol as a mandatory step in multiple cellular metabolic pathways4,5.
Throughout the process, an electrochemical proton gradient is created across the mitochondrial inner membrane, which is transformed into biologically active energy by the ATP synthase complex V2. Consequently, mitochondrial dysfunction leads to a myriad of pathological conditions mainly affecting tissues with high-energy requirements-the brain, heart, and skeletal muscle6,7. Therefore, it is fundamental to develop methods to accurately analyze mitochondrial bioenergetics to investigate its role in health and disease, particularly in highly energetic tissues such as skeletal muscles.
The Clark-type oxygen electrode has been classically used in the study of mitochondrial respiration8. However, this system has been progressively displaced by higher-resolution technologies, with microplate-based oxygen consumption technologies such as Agilent Seahorse XF analyzers being especially popular9. In the skeletal muscle field, these studies are typically conducted in cultured cells, mainly in the C2C12 immortalized mouse myoblast cell line or primary cultures derived from satellite cells10,11. However, these studies do not fully recapitulate the situation in vivo, especially when investigating mitochondrial biology and function at the tissue level upon specific insults, nongenetic interventions, or genetic manipulations.
Furthermore, respiration assays in cells are more complex due to additional factors, including extra-mitochondrial demand of ATP and assay substrates or signaling events, which could mislead the interpretation of the results. Alternatively, it is also possible to use single or bundles of freshly isolated myofibers from muscles. However, the isolation method is technically challenging and only feasible for a few muscle types. In this case, flexor digitorum brevis (FDB) and extensor digitorum longus (EDL) muscles are mainly used10,12,13, although a few reports describe the use of other muscle types as well14,15.
Bioenergetic profiling of skeletal muscle sections has also been reported16. The major advantage of this method is that intact muscles can be studied (the authors show that slicing through fibers does not disturb results when compared with isolated myofibers). However, mitochondrial access to substrates and assay inhibitors is limited, and thus, only a few parameters can be measured16. Finally, isolated mitochondria can be likewise employed9,17,18,19. In this case, mitochondria lose their cytosolic environment, which could affect their function. In contrast, this method guarantees access to substrates and inhibitors, enables the analysis of a plethora of sample types, and typically requires less material.
This paper describes a method to perform the bioenergetic profiling of isolated mitochondria from mouse skeletal muscle using microplate-based respirometric assays (Figure 1). In particular, three protocols are detailed: the Coupling Assay, CA to assess the degree of coupling between the ETC and the OXPHOS machinery; the Electron Flow Assay, EFA to measure the activity of the individual ETC complexes; and the BOX assay to determine mitochondrial &#946;-oxidation capacity. Notably, only small amounts of samples are required compared with conventional respirometry methods. The isolation protocol used here has been modified from the method published elsewhere18.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>ADP</td>
			<td>Sigma</td>
			<td>A5285</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>AKT antibody</td>
			<td>Cell Signaling Technology</td>
			<td>C67E7</td>
			<td>Rabbit (Host species)</td>
		</tr>
		<tr>
			<td>anti-Goat HRP</td>
			<td>Sigma</td>
			<td>401504</td>
			<td>Rabbit (Host species)</td>
		</tr>
		<tr>
			<td>anti-Mouse HRP</td>
			<td>Cell Signaling</td>
			<td>#7076</td>
			<td>Horse (Host species)</td>
		</tr>
		<tr>
			<td>Antimycin A</td>
			<td>Sigma</td>
			<td>A8674</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>anti-Rabbit HRP</td>
			<td>Cell Signaling</td>
			<td>#7074</td>
			<td>Goat (Host species)</td>
		</tr>
		<tr>
			<td>Ascorbic acid</td>
			<td>Sigma</td>
			<td>A5960</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Bactin antibody</td>
			<td>Sigma</td>
			<td>MBS4-48085</td>
			<td>Goat (Host species)</td>
		</tr>
		<tr>
			<td>Bio-Rad Protein Assay Kit II</td>
			<td>Bio-Rad</td>
			<td>5000002</td>
			<td>It includes 5x Bradford reagent and BSA of known concentration for the standard curve</td>
		</tr>
		<tr>
			<td>BSA, fraction V, Fatty Acid-Free</td>
			<td>Calbiochem</td>
			<td>126575</td>
			<td>Stock at 4 &#176;C</td>
		</tr>
		<tr>
			<td>C tube</td>
			<td>Miltenyi Biotec</td>
			<td>130-093-237</td>
			<td>Purple lid</td>
		</tr>
		<tr>
			<td>Calnexin antibody</td>
			<td>ThermoFisher</td>
			<td>MA3-027</td>
			<td>Mouse (Host species)</td>
		</tr>
		<tr>
			<td>D-mannitol</td>
			<td>Sigma</td>
			<td>M4125</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>BDH</td>
			<td>280254D</td>
			<td>Stock at 4 &#176;C</td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma</td>
			<td>E-4378</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>FCCP</td>
			<td>Sigma</td>
			<td>C2920</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>gentleMACS Dissociator</td>
			<td>Miltenyi Biotec</td>
			<td>130-093-235</td>
			<td>Homogenizer</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma</td>
			<td>H3375</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>HSP70 antibody</td>
			<td>Proteintech</td>
			<td>10995-1-AP</td>
			<td>Rabbit (Host species)</td>
		</tr>
		<tr>
			<td>LDH-A antibody</td>
			<td>Santa Cruz Biotechnology</td>
			<td>SC27230</td>
			<td>Goat (Host species)</td>
		</tr>
		<tr>
			<td>Magnesium chloride</td>
			<td>ChemCruz</td>
			<td>sc-255260A</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Malic acid</td>
			<td>Sigma</td>
			<td>P1645</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Microplate spectrophotometer</td>
			<td>BMG LABTECH GmbH</td>
			<td>POLARstar OMEGA S/N 415-0292</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Milli-Q water</td>
			<td>Millipore system</td>
			<td>F7HA17757A</td>
			<td>Ultrapure water</td>
		</tr>
		<tr>
			<td>mtTFA antibody</td>
			<td>Santa Cruz Biotechnology</td>
			<td>SC23588</td>
			<td>Goat (Host species)</td>
		</tr>
		<tr>
			<td>Na+/K+-ATPase &#945;1 antibody</td>
			<td>Novus Biologicals</td>
			<td>NB300-14755</td>
			<td>Mouse (Host species)</td>
		</tr>
		<tr>
			<td>Oligomycin</td>
			<td>Sigma</td>
			<td>O4876</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>Palmitoyl-L-carnitine</td>
			<td>Sigma</td>
			<td>P1645</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>PBS tablets</td>
			<td>Sigma</td>
			<td>P4417-100TAB</td>
			<td>1x stock at RT</td>
		</tr>
		<tr>
			<td>Potassium dihydrogen phosphate</td>
			<td>ChemCruz</td>
			<td>sc-203211</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Potassium hydroxide</td>
			<td>Sigma</td>
			<td>60377</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Pyruvic acid</td>
			<td>Sigma</td>
			<td>107360</td>
			<td>Stock at 4 &#176;C</td>
		</tr>
		<tr>
			<td>Rotenone</td>
			<td>Sigma</td>
			<td>R8875</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>Seahorse XF24 mitochondrial flux analyzer</td>
			<td>Agilent Technologies</td>
			<td>420179</td>
			<td>XFe24 model</td>
		</tr>
		<tr>
			<td>Seahorse XFe24 FluxPak mini</td>
			<td>Agilent Technologies</td>
			<td>102342-100</td>
			<td>The kit includes cartridges, microplates, and calibrant solution</td>
		</tr>
		<tr>
			<td>Succinate</td>
			<td>Sigma</td>
			<td>S7626</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma</td>
			<td>S9378</td>
			<td>Stock at RT</td>
		</tr>
		<tr>
			<td>TIMM23 antibody</td>
			<td>Abcam</td>
			<td>ab230253</td>
			<td>Rabbit (Host species)</td>
		</tr>
		<tr>
			<td>TMPD</td>
			<td>Sigma</td>
			<td>T7394</td>
			<td>Stock at -20 &#176;C</td>
		</tr>
		<tr>
			<td>TOMM20 antibody</td>
			<td>Abcam</td>
			<td>ab56783</td>
			<td>Mouse (Host species)</td>
		</tr>
		<tr>
			<td>VDAC antibody</td>
			<td>Abcam</td>
			<td>ab15895</td>
			<td>Rabbit (Host species)</td>
		</tr>
	</tbody>
</table>

isolation of mitochondria from mouse skeletal muscle for respirometric assays

Most of the cell&#39;s energy is obtained through the degradation of glucose, fatty acids, and amino acids by different pathways that converge on the mitochondrial oxidative phosphorylation (OXPHOS) system, which is regulated in response to cellular demands. The lipid molecule Coenzyme Q (CoQ) is essential in this process by transferring electrons to complex III in the electron transport chain (ETC) through constant oxidation/reduction cycles. Mitochondria status and, ultimately, cellular health can be assessed by measuring ETC oxygen consumption using respirometric assays. These studies are typically performed in established or primary cell lines that have been cultured for several days. In both cases, the respiration parameters obtained may have deviated from normal physiological conditions in&#160;any given organ or tissue.
Additionally, the intrinsic characteristics of cultured single fibers isolated from skeletal muscle impede this type of analysis. This paper presents an updated and detailed protocol for the analysis of respiration in freshly isolated mitochondria from mouse skeletal muscle. We also provide solutions to potential problems that could arise at any step of the process. The method presented here could be applied to compare oxygen consumption rates in diverse transgenic mouse models and study the mitochondrial response to drug treatments or other factors such as aging or sex. This is a feasible method to respond to crucial questions about mitochondrial bioenergetics metabolism and regulation.

The protocol presented here allows the in vivo analysis of mitochondrial respiration through the isolation of mitochondria from mouse skeletal muscle. An outline of the method is shown in Figure 1. After dissecting skeletal muscles from the hindlimbs (Figure 2), tissues are homogenized and mitochondria purified, under isotonic conditions, through serial centrifugations. The purity of the different fractions obtained during the isolation process can be a...

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Isolation of Mitochondria from Mouse Skeletal Muscle for Respirometric Assays

Here, we describe a detailed method for mitochondria isolation from mouse skeletal muscle and the subsequent analysis of respiration by Oxygen Consumption Rate (OCR) using microplate-based respirometric assays. This pipeline can be applied to study the effects of multiple environmental or genetic interventions on mitochondrial metabolism.

Most of the cell&#39;s energy is obtained through the degradation of glucose, fatty acids, and amino acids by different pathways that converge on the ...

This word describes respiration analysis in processing mitochondria from mouse skeletal muscle. This protocol considerably reduce purification time and allows multiple samples to be processed simultaneously. Mitochondria from animals at any eight gender of United background can be mutilated using this protocol enabling the study of respiration in a wide variety of experimental conditions.This method is suitable for all research areas where mitochondria function is relevant including aging, drug testing, cancer, or development. It can even be adapted to other tissues and organisms as well. Ensure all materials are cold by placing everything on the ice during the procedure to protect mitochondria from damage.Place three 50 milliliter beakers per sample on ice and add 10 milliliters of PBS in beaker one, 10 milliliters of 10 millimolar EDTA PBS in beaker two, and four milliliters IB1 in beaker three. Spray the right hind limb of a euthanized mouse with 70%ethanol to prevent fur from shedding and tape the limb to the cork dissection board then tape the left fore limb. Make an incision with a sterile disposable scalpel through the skin from knee to toe.Grip the skin with toothed forceps at ankle level and cut it with fine scissors around the ankle. Ease the skin away from the underlying musculature with fine tip tweezers in one hand while pulling it up with toothed forceps in the other hand. Dissect all skeletal muscles from ankle to knee and remove all connective tissue over the tibialis anterior muscle using fine tweezers and scissors.Find the four distal tendons of the extensor digitorum longus muscle and section them close to their insertions in the toes. Locate the tibialis anterior distal tendon and cut it close to its insertion below the ankle. Pull the tibialis anterior and extensor digitorum longus tendons above the ankle to liberate the loose ends.Grip the loose ends of the tendons and ease the muscles away from the rest of the musculature in bones by pulling them up. Cut the proximal tendons of these muscles as close as possible to the kneecap. Turn the mouse upside down to proceed with gastrocnemius and soleus muscle extraction.Grip the pocket formed between the biceps, femoris, and the gastrocnemius and separate these muscles using fine scissors to visualize the proximal gastrocnemius tendon. Grip and carefully cut the distal Achilles tendon with fine scissors. Cut the proximal gastrocnemius tendon liberating it with the underlying soleus.Carefully dissect the remaining muscles and re-pin the mouse in the initial position to dissect the quadriceps muscle. Discard the adipose tissue then insert fine tweezers between the quadriceps and the femur to separate the muscle from the bone. Grip the distal quadriceps muscle tendons and cut the tendon as close as possible to the kneecap.Pull the quadriceps up and liberate them with fine scissors at the proximal insertion. Repeat the same for the left hind limb. Rinse all the muscles in beaker one, then two, followed by beaker three.Finally, mince all the muscles in beaker three with sharp scissors on ice. Transfer the suspension to a C tube, tightly close it, and attach it upside down onto the sleeve of the homogenizer. Divide the homogenate into two 2 milliliter pre-chilled micro centrifuge tubes and centrifuge for 10 minutes.Then transfer the supernatant to new pre-chilled tubes and centrifuge for another 10 minutes. Combine the pellet in 500 microliters of IB2 Transfer the supernatant to a new 2 milliliter pre-chilled micro centrifuge tube and label it as supernatant number two, or SN2. Re suspend the final mitochondrial pellet in 200 microliters of re suspension buffer.Quickly set aside 10 microliters for protein quantification and immediately add 10 microliters of 10%FFA BSA to the remaining mitochondrial suspension to prevent damage. Centrifuge the concentrated mitochondrial suspension at 10, 500 times G for 10 minutes at four degrees Celsius. Re suspend the mitochondrial pellet in 100 microliters of 1X coupling assay medium with BSA, 1X electron flow assay medium with BSA, or 1X beta oxidation medium with BSA, depending on the protocol to be performed.Dilute this concentrated mitochondrial sample to 0.2 micrograms per microliter using the corresponding assay medium. Seed 50 microliters of the suspension per well in a pre-chilled 24 well micro plate on ice. In the background correction wells, add the corresponding assay medium only.Store the remaining mitochondrial suspension at minus 80 degrees Celsius for fragmentation purity determination. Spin the micro plate in the pre chilled preparative centrifuge for 20 minutes. In the meantime, warm the remaining assay medium to 37 degrees Celsius.After centrifugation, leave the micro plate on the bench for five minutes to equilibrate. Add 450 microliters of the warm assay medium per well slowly and carefully to avoid detaching of mitochondria. Place the micro plate immediately in the oxygen consumption measuring instrument without the lid and start the measurement program.Ensure that the first step is a 10 minute incubation to allow the micro plate to warm up. Once the experiment is finished, remove the cartridge and micro plate, switch off the instrument, and start the analysis. General protein profiles from the different fractions obtained through serial centrifugations showed distinct protein populations in the isolated fractions.The presence of all the mitochondrial content is evident by the strong signals for markers of the outer and inner mitochondrial membrane and nucleoid associated proteins. Fraction N represents nuclei and undisrupted material. Most of the endoplasmic reticulum, plasma membrane, or cytoplasm markers in the SN1 or SN2 fractions highlight the high purity obtained during isolation.An increase in oxygen consumption was observed after ADP addition in the coupling and beta oxidation assays. After carbonyl cyanide-p-trifluoromethoxy phenylhydrazone addition, oxygen consumption reached its highest level. A low respiratory control ratio ensures the integrity of the isolated mitochondria.The electron flow assay examined the activity of the electron transport chain complexes individually or in combination through the injection of specific substrates and inhibitors. Isolating mitochondria are extremely sensitive. Hence all the steps after tissue mitigation need to be performed diligently and carefully to preserve their viability.Experimental assays can be complimented with a deterministic sematic analysis of key mitochondria molecules or with the study of the assembly of respirometric complexes using blue native polyacrylamide gel electrophoresis.

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Adult and Embryonic Skeletal Muscle Microexplant Culture and Isolation of Skeletal Muscle Stem Cells

Cultured embryonic and adult skeletal muscle cells have a number of different uses. The micro-dissected explants technique described in this chapter is a robust and reliable method for isolating relatively large numbers of proliferative skeletal muscle cells from juvenile, adult or embryonic muscles as a source of skeletal muscle stem cells. The authors have used micro-dissected explant cultures to analyse the growth characteristics of skeletal muscle cells in wild-type and dystrophic muscles. Each of the components of tissue growth, namely cell survival, proliferation, senescence and differentiation can be analysed separately using the methods described here. The net effect of all components of growth can be established by means of measuring explant outgrowth rates. The micro-explant method can be used to establish primary cultures from a wide range of different muscle types and ages and, as described here, has been adapted by the authors to enable the isolation of embryonic skeletal muscle precursors.
Uniquely, micro-explant cultures have been used to derive clonal (single cell origin) skeletal muscle stem cell (SMSc) lines which can be expanded and used for in vivo transplantation. In vivo transplanted SMSc behave as functional, tissue-specific, satellite cells which contribute to skeletal muscle fibre regeneration but which are also retained (in the satellite cell niche) as a small pool of undifferentiated stem cells which can be re-isolated into culture using the micro-explant method.

The micro-dissected explants technique is a robust and reliable method for isolating proliferative skeletal muscle cells from juvenile, adult or embryonic muscles as a source of skeletal muscle stem cells. Uniquely, these cells have been clonally derived to produce skeletal muscle stem cell lines used for in vivo transplantation.

Cultured embryonic and adult skeletal muscle cells have a number of different uses. The micro-dissected explants technique described in this chapter is a ...

Mitochondrial Isolation from Skeletal Muscle

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and regulate a number of signaling cascades2,3. Past and current researchers have isolated mitochondria from rat and mice tissues such as liver, brain and heart4,5. In recent years, many researchers have focused on studying mitochondrial function from skeletal muscles.
Here, we describe a method that we have used successfully for the isolation of mitochondria from skeletal muscles 6. Our procedure requires that all buffers and reagents are made fresh and need about 250-500 mg of skeletal muscle. We studied mitochondria isolated from rat and mouse gastrocnemius and diaphragm, and rat extraocular muscles. Mitochondrial protein concentration is measured with the Bradford assay. It is important that mitochondrial samples be kept ice-cold during preparation and that functional studies be performed within a relatively short time (~1 hr). Mitochondrial respiration is measured using polarography with a Clark-type electrode (Oxygraph system) at 37&deg;C7. Calibration of the oxygen electrode is a key step in this protocol and it must be performed daily. Isolated mitochondria (150 &mu;g) are added to 0.5 ml of experimental buffer (EB). State 2 respiration starts with addition of glutamate (5mM) and malate (2.5 mM). Then, adenosine diphosphate (ADP) (150 &mu;M) is added to start state 3. Oligomycin (1 &mu;M), an ATPase synthase blocker, is used to estimate state 4. Lastly, carbonyl cyanide p-[trifluoromethoxy]-phenyl-hydrazone (FCCP, 0.2 &mu;M) is added to measurestate 5, or uncoupled respiration 6. The respiratory control ratio (RCR), the ratio of state 3 to state 4, is calculated after each experiment. An RCR &ge;4 is considered as evidence of a viable mitochondria preparation.
In summary, we present a method for the isolation of viable mitochondria from skeletal muscles that can be used in biochemical (e.g., enzyme activity, immunodetection, proteomics) and functional studies (mitochondrial respiration).

This protocol describes a procedure to study the respiration of mitochondria isolated from skeletal muscles. This method was adapted from Scorrano et al. (2007). The mitochondrial isolation procedure requires about 2 hours. The mitochondrial respiration can be completed in about 1 hour.

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and ...

Purification of Progenitors from Skeletal Muscle

Skeletal muscle contains multiple progenitor populations of distinct embryonic origins and developmental potential. Myogenic progenitors, usually residing in a "satellite cell position" between the myofiber plasma membrane and the laminin-rich basement membrane that ensheaths it, are self-renewing cells that are solely committed to the myogenic lineage1,2. We have recently described a second class of vessel associated progenitors that can generate myofibroblasts and white adipocytes, which responds to damage by efficiently entering proliferation and provides trophic support to myogenic cells during tissue regeneration3,4. One of the most trusted assays to determine the developmental and regenerative potential of a given cell population relies on their isolation and transplantation5-7. To this end we have optimized protocols for their purification by flow cytometry from enzymatically dissociated muscle, which we will outline in this article. The populations obtained using this method will contain either myogenic or fibro/adipogenic colony forming cells: no other cell types are capable of expanding in vitro or surviving in vivo delivery. However, when these populations are used immediately after the sort for molecular analysis (e.g qRT-PCR) one must keep in mind that the freshly sorted subsets may contain other contaminant cells that lack the ability of forming colonies or engrafting recipients.

Method for the enzymatic dissociation, surface labeling and purification by flow cytometry of fibro/adipogenic and myogenic progenitors from murine skeletal muscle.

Skeletal muscle contains multiple progenitor populations of distinct embryonic origins and developmental potential. Myogenic progenitors, usually residing ...

Laser-inflicted Injury of Zebrafish Embryonic Skeletal Muscle

Various experimental approaches have been used in mouse to induce muscle injury with the aim to study muscle regeneration, including myotoxin injections (bupivacaine, cardiotoxin or notexin), muscle transplantations (denervation-devascularization induced regeneration), intensive exercise, but also murine muscular dystrophy models such as the mdx mouse (for a review of these approaches see 1). In zebrafish, genetic approaches include mutants that exhibit muscular dystrophy phenotypes (such as runzel2 or sapje3) and antisense oligonucleotide morpholinos that block the expression of dystrophy-associated genes4. Besides, chemical approaches are also possible, e.g. with Galanthamine, a chemical compound inhibiting acetylcholinesterase, thereby resulting in hypercontraction, which eventually leads to muscular dystrophy5. However, genetic and pharmacological approaches generally affect all muscles within an individual, whereas the extent of physically inflicted injuries are more easily controlled spatially and temporally1. Localized physical injury allows the assessment of contralateral muscle as an internal control. Indeed, we recently used laser-mediated cell ablation to study skeletal muscle regeneration in the zebrafish embryo6, while another group recently reported the use of a two-photon laser (822 nm) to damage very locally the plasma membrane of individual embryonic zebrafish muscle cells7.
Here, we report a method for using the micropoint laser (Andor Technology) for skeletal muscle cell injury in the zebrafish embryo. The micropoint laser is a high energy laser which is suitable for targeted cell ablation at a wavelength of 435 nm. The laser is connected to a microscope (in our setup, an optical microscope from Zeiss) in such a way that the microscope can be used at the same time for focusing the laser light onto the sample and for visualizing the effects of the wounding (brightfield or fluorescence). The parameters for controlling laser pulses include wavelength, intensity, and number of pulses.
Due to its transparency and external embryonic development, the zebrafish embryo is highly amenable for both laser-induced injury and for studying the subsequent recovery. Between 1 and 2 days post-fertilization, somitic skeletal muscle cells progressively undergo maturation from anterior to posterior due to the progression of somitogenesis from the trunk to the tail8, 9. At these stages, embryos spontaneously twitch and initiate swimming. The zebrafish has recently been recognized as an important vertebrate model organism for the study of tissue regeneration, as many types of tissues (cardiac, neuronal, vascular etc.) can be regenerated after injury in the adult zebrafish10, 11.

The method presented here comprises the precise injury of live zebrafish embryos with high-energy laser pulses and the subsequent analysis of these injuries and their recovery with time. We also show how genetically labeled single or groups of skeletal muscle cells can be tracked during and after laser light induced damage.

Various experimental approaches have been used in mouse to induce muscle injury with the aim to study muscle regeneration, including myotoxin injections ...

Isolation and Culture of Individual Myofibers and their Satellite Cells from Adult Skeletal Muscle

Muscle regeneration in the adult is performed by resident stem cells called satellite cells. Satellite cells are defined by their position between the basal lamina and the sarcolemma of each myofiber. Current knowledge of their behavior heavily relies on the use of the single myofiber isolation protocol. In 1985, Bischoff described a protocol to isolate single live fibers from the Flexor Digitorum Brevis (FDB) of adult rats with the goal to create an in vitro system in which the physical association between the myofiber and its stem cells is preserved 1. In 1995, Rosenblattmodified the Bischoff protocol such that myofibers are singly picked and handled separately after collagenase digestion instead of being isolated by gravity sedimentation 2, 3. The Rosenblatt or Bischoff protocol has since been adapted to different muscles, age or conditions 3-6. The single myofiber isolation technique is an indispensable tool due its unique advantages. First, in the single myofiber protocol, satellite cells are maintained beneath the basal lamina. This is a unique feature of the protocol as other techniques such as Fluorescence Activated Cell Sorting require chemical and mechanical tissue dissociation 7. Although the myofiber culture system cannot substitute for in vivo studies, it does offer an excellent platform to address relevant biological properties of muscle stem cells. Single myofibers can be cultured in standard plating conditions or in floating conditions. Satellite cells on floating myofibers are subjected to virtually no other influence than the myofiber environment. Substrate stiffness and coating have been shown to influence satellite cells' ability to regenerate muscles 8, 9 so being able to control each of these factors independently allows discrimination between niche-dependent and -independent responses. Different concentrations of serum have also been shown to have an effect on the transition from quiescence to activation. To preserve the quiescence state of its associated satellite cells, fibers should be kept in low serum medium 1-3. This is particularly useful when studying genes involved in the quiescence state. In serum rich medium, satellite cells quickly activate, proliferate, migrate and differentiate, thus mimicking the in vivo regenerative process 1-3. The system can be used to perform a variety of assays such as the testing of chemical inhibitors; ectopic expression of genes by virus delivery; oligonucleotide based gene knock-down or live imaging. This video article describes the protocol currently used in our laboratory to isolate single myofibers from the Extensor Digitorum Longus (EDL) muscle of adult mice (6-8 weeks old).

Isolation and culture of myofibers is the gold standard in vitro system to study the transition of satellite cells through quiescence, activation and differentiation. Importantly, the single myofiber culture system preserves the myofiber/stem cell association, which is an essential component of the muscle stem cell niche.

Muscle  regeneration in the adult is performed by resident stem cells called satellite  cells. Satellite cells are defined by  their position between the ...

Analysis of Skeletal Muscle Defects in Larval Zebrafish by Birefringence and Touch-evoke Escape Response Assays

Zebrafish (Danio rerio) have become a particularly effective tool for modeling human diseases affecting skeletal muscle, including muscular dystrophies1-3, congenital myopathies4,5, and disruptions in sarcomeric assembly6,7, due to high genomic and structural conservation with mammals8. Muscular disorganization and locomotive impairment can be quickly assessed in the zebrafish over the first few days post-fertilization. Two assays to help characterize skeletal muscle defects in zebrafish are birefringence (structural) and touch-evoked escape response (behavioral).
Birefringence is a physical property in which light is rotated as it passes through ordered matter, such as the pseudo-crystalline array of muscle sarcomeres9. It is a simple, noninvasive approach to assess muscle integrity in translucent zebrafish larvae early in development. Wild-type zebrafish with highly organized skeletal muscle appear very bright amidst a dark background when visualized between two polarized light filters, whereas muscle mutants have birefringence patterns specific to the primary muscular disorder they model. Zebrafish modeling muscular dystrophies, diseases characterized by myofiber degeneration followed by repeated rounds of regeneration, exhibit degenerative dark patches in skeletal muscle under polarized light. Nondystrophic myopathies are not associated with necrosis or regenerative changes, but result in disorganized myofibers and skeletal muscle weakness. Myopathic zebrafish typically show an overall reduction in birefringence, reflecting the disorganization of sarcomeres.
The touch-evoked escape assay involves observing an embryo&#39;s swimming behavior in response to tactile stimulation10-12. In comparison to wild-type larvae, mutant larvae frequently display a weak escape contraction, followed by slow swimming or other type of impaired motion that fails to propel the larvae more than a short distance12. The advantage of these assays is that disease progression in the same fish type can be monitored in vivo for several days, and that large numbers of fish can be analyzed in a short time relative to higher vertebrates.

The zebrafish is now an established and powerful tool for modeling muscular dystrophies, congenital myopathies, and related neuromuscular diseases. Birefringence and touch-evoked escape behavior are two common noninvasive assays used to determine the degree of muscular disorganization and locomotive impairment of zebrafish embryos during early development.

Zebrafish (Danio rerio) have become a particularly effective tool for modeling human diseases affecting skeletal muscle, including muscular ...

Isolation of Blood-vessel-derived Multipotent Precursors from Human Skeletal Muscle

Since the discovery of mesenchymal stem/stromal cells (MSCs), the native identity and localization&#160;of MSCs have been obscured by their retrospective isolation in culture. Recently, using fluorescence-activated cell sorting (FACS), we and other researchers prospectively identified and purified three subpopulations of multipotent precursor cells associated with the vasculature of human skeletal muscle. These three cell populations: myogenic endothelial cells (MECs), pericytes (PCs), and adventitial cells (ACs), are localized respectively to the three structural layers of blood vessels: intima, media, and adventitia. All of these human blood-vessel-derived stem cell (hBVSC) populations not only express classic MSC markers but also possess mesodermal developmental potentials similar to typical MSCs. Previously, MECs, PCs, and ACs have been isolated through distinct protocols and subsequently characterized in separate studies. The current isolation protocol, through modifications to the isolation process and adjustments in the selective cell surface markers, allows us to simultaneously purify all three hBVSC subpopulations by FACS from a single human muscle biopsy. This new method will not only streamline the isolation of multiple BVSC subpopulations but also facilitate future clinical applications of hBVSCs for distinct therapeutic purposes.

Blood vessels within human skeletal muscle harbor several multi-lineage precursor populations that are ideal for regenerative applications. This isolation method allows simultaneous purification of three multipotent precursor cell populations respectively from three structural layers of blood vessels: myogenic endothelial cells from intima, pericytes from media, and adventitial cells from adventitia.

Since the discovery of mesenchymal stem/stromal cells (MSCs), the native identity and localization&#160;of MSCs have been obscured by their retrospective ...

Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue

Comparison between two or more distinct groups, such as healthy vs. disease, is necessary to determine cellular status. Mitochondria are at the nexus of cell heath due to their role in both cell metabolism and energy production as well as control of apoptosis. Therefore, direct evaluation of isolated mitochondria and mitochondrial perturbation offers the ability to determine if organelle-specific (dys)function is occurring. The methods described in this protocol include isolation of intact, functional mitochondria from HEK cultured cells and mouse liver and spinal cord, but can be easily adapted for use with other cultured cells or animal tissues. Mitochondrial function assessed by TMRE and the use of common mitochondrial uncouplers and inhibitors in conjunction with a fluorescent plate reader allow this protocol not only to be versatile and accessible to most research laboratories, but also offers high throughput.

Comparison of mitochondrial membrane potential between samples yields valuable information about cellular status. Detailed steps for isolating mitochondria and assessing response to inhibitors and uncouplers using fluorescence are described. The method and utility of this protocol are illustrated by use of a cell culture and animal model of cellular stress.

Comparison between two or more distinct groups, such as healthy vs. disease, is necessary to determine cellular status. Mitochondria are at the nexus of ...

Isolation of Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High Throughput Microplate Respiratory Measurements

Dysfunctional skeletal muscle mitochondria play a role in altered metabolism observed with aging, obesity and Type II diabetes. Mitochondrial respirometric assays from isolated mitochondrial preparations allow for the assessment of mitochondrial function, as well as determination of the mechanism(s) of action of drugs and proteins that modulate metabolism. Current isolation procedures often require large quantities of tissue to yield high quality mitochondria necessary for respirometric assays. The methods presented herein describe how high quality purified mitochondria (~ 450 &#181;g) can be isolated from minimal quantities (~75-100 mg) of mouse skeletal muscle for use in high throughput respiratory measurements. We determined that our isolation method yields 92.5&#177; 2.0% intact mitochondria by measuring citrate synthase activity spectrophotometrically. In addition, Western blot analysis in isolated mitochondria resulted in the faint expression of the cytosolic protein, GAPDH, and the robust expression of the mitochondrial protein, COXIV. The absence of a prominent GAPDH band in the isolated mitochondria is indicative of little contamination from non-mitochondrial sources during the isolation procedure. Most importantly, the measurement of O2 consumption rate with micro-plate based technology and determining the respiratory control ratio (RCR) for coupled respirometric assays shows highly coupled (RCR; &#62;6 for all assays) and functional mitochondria. In conclusion, the addition of a separate mincing step and significantly reducing motor driven homogenization speed of a previously reported method has allowed the isolation of high quality and purified mitochondria from smaller quantities of mouse skeletal muscle that results in highly coupled mitochondria that respire with high function during microplate based respirometirc assays.

Here, we present a modification of a previously reported method that allows for the isolation of high quality and purified mitochondria from smaller quantities of mouse skeletal muscle. This procedure results in highly coupled mitochondria that respire with high function during microplate based respirometirc assays.

Dysfunctional skeletal muscle mitochondria play a role in altered metabolism observed with aging, obesity and Type II diabetes. Mitochondrial ...

Isolation of Intact Mitochondria from Skeletal Muscle by Differential Centrifugation for High-resolution Respirometry Measurements

Mitochondria are involved in cellular energy metabolism and use oxygen to produce energy in the form of adenosine triphosphate (ATP). Differential centrifugation at low- and high-speed is commonly used to isolate mitochondria from tissues and cultured cells. Crude mitochondrial fractions obtained by differential centrifugation are used for respirometry measurements. The differential centrifugation technique is based on the separation of organelles according to their size and sedimentation velocity. The isolation of mitochondria is performed immediately after tissue harvesting. The tissue is immersed in an ice-cold homogenization medium, minced using scissors and homogenized in a glass homogenizer with a loose-fitting pestle. The differential centrifugation technique is efficient, fast and inexpensive and the mitochondria obtained by differential centrifugation are pure enough for respirometry assays. Some of the limitations and disadvantages of isolated mitochondria, based on differential centrifugation, are that the mitochondria can be damaged during the homogenization and isolation procedure and that large amounts of the tissue biopsy or cultured cells are required for the mitochondrial isolation.

Here, a quadriceps muscle specimen is taken from an anaesthetized pig and mitochondria are isolated by differential centrifugation. Then, the respiratory rates of mitochondrial respiratory chain complexes I, II and IV are determined using high-resolution respirometry.