Name: measuring trans-plasma membrane electron transport by c2c12 myotubes
Uploaded: 2018-05-04T15:00:00
Description: Watch this Scientific Journal Video about Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes at JoVE.com

We would like to thank Thomas Bell, Lyn Mattathil, Mark Mannino, and Neej Patel for their technical support. This work was supported by United States Public Health Service award R15DK102122 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) to Jonathan Fisher. The manuscript content is solely the responsibility of the authors and does not necessarily represent the official views of the NIDDK or the National Institutes of Health.

NOTE: See Figure 1 for a schematic overview of key steps.
1. WST-1 Reduction Assay
<ol>
	<li>Grow and differentiate C2C12 adherent cells using standard cell culture procedures7 in a 96-well plate utilizing rows A-F.
	<ol>
		<li>Use a differentiation medium consisting of Dulbecco&#39;s Modified Eagle&#39;s Medium (DMEM) supplemented with 2% horse serum, 100 U/mL penicillin, and 0.1 mg/mL streptomycin. Incubate the cells at 37 &#176;C with ...

<ol>
	<li>Kilberg, M. S., Christensen, H. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron-transferring+enzymes+in+the+plasma+membrane+of+the+Ehrlich+ascites+tumor+cell.">Electron-transferring enzymes in the plasma membrane of the Ehrlich ascites tumor cell.</a> Biochemistry. 18 (8), 1525-1530 (1979).</li><li>Crane, F. L., Roberts, H., Linnane, A. W., Low, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transmembrane+ferricyanide+reduction+by+cells+of+the+yeast+Saccharomyces+cerevisiae.">Transmembrane ferricyanide reduction by cells of the yeast Saccharomyces cerevisiae.</a> J Bioenerg Biomembr. 14 (3), 191-205 (1982).</li><li>Craig, T. A., Crane, F. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+trans-plasma+membrane+electron+transport+system+in+plact+cells.">Evidence for trans-plasma membrane electron transport system in plact cells.</a> Proc. Indiana Acad. Sci. 90, 150-155 (1981).</li><li>Mishra, R. K., Passow, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+intracellular+ATP+synthesis+by+extracellular+ferricyanide+in+human+red+blood+cells.">Induction of intracellular ATP synthesis by extracellular ferricyanide in human red blood cells.</a> J Membr Biol. 1 (1), 214-224 (1969).</li><li>Crane, F. L., Sun, I. L., Clark, M. G., Grenbing, C., Low, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplasma-membrane+redox+systems+in+growth+and+development.">Transplasma-membrane redox systems in growth and development.</a> Biochim Biophys Acta. 811, 233-264 (1985).</li><li>Berridge, M. V., Tan, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trans-plasma+membrane+electron+transport:+a+cellular+assay+for+NADH-+and+NADPH-oxidase+based+on+extracellular,+superoxide-mediated+reduction+of+the+sulfonated+tetrazolium+salt+WST-1.">Trans-plasma membrane electron transport: a cellular assay for NADH- and NADPH-oxidase based on extracellular, superoxide-mediated reduction of the sulfonated tetrazolium salt WST-1.</a> Protoplasma. 205 (1-4), 74-82 (1998).</li><li>Eccardt, A. 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=Trans-plasma+membrane+electron+transport+and+ascorbate+efflux+by+skeletal+muscle.">Trans-plasma membrane electron transport and ascorbate efflux by skeletal muscle.</a> Antioxidants. 6 (4), 89 (2017).</li><li>Sun, I. L., Navas, P., Crane, F. L., Morre, D. J., Low, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NADH+diferric+transferrin+reductase+in+liver+plasma+membrane.">NADH diferric transferrin reductase in liver plasma membrane.</a> J Biol Chem. 262 (33), 15915-15921 (1987).</li><li>Larm, J. A., Vaillant, F., Linnane, A. W., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Up-regulation+of+the+plasma+membrane+oxidoreductase+as+a+prerequisite+for+the+viability+of+human+Namalwa+rho+0+cells.">Up-regulation of the plasma membrane oxidoreductase as a prerequisite for the viability of human Namalwa rho 0 cells.</a> J Biol Chem. 269 (48), 30097-30100 (1994).</li><li>Inman, R. S., Coughlan, M. M., Wessling-Resnik, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+ferrireductase+activity+of+K562+cells+is+coupled+to+transferrin-independent+iron+transport.">Extracellular ferrireductase activity of K562 cells is coupled to transferrin-independent iron transport.</a> Biochemistry. 33, 11850-11857 (1994).</li><li>Castillo-Olivares, A., Esteban del Valle, A., Marquez, J., Nunez de Castro, I., Medina, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ehrlich+cell+plasma+membrane+redox+system+is+modulated+through+signal+transduction+pathways+involving+cGMP+and+Ca2++as+second+messengers.">Ehrlich cell plasma membrane redox system is modulated through signal transduction pathways involving cGMP and Ca2+ as second messengers.</a> J Bioenerg Biomembr. 27 (6), 605-611 (1995).</li><li>Medina, M. A., del Castillo-Olivares, A., Nunez de Castro, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multifunctional+plasma+membrane+redox+systems.">Multifunctional plasma membrane redox systems.</a> Bioessays. 19 (11), 977-984 (1997).</li><li>Medina, M. A., del Castillo-Olivares, A., Schweigerer, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasma+membrane+redox+activity+correlates+with+N-myc+expression+in+neuroblastoma+cells.">Plasma membrane redox activity correlates with N-myc expression in neuroblastoma cells.</a> FEBS Lett. 311 (2), 99-101 (1992).</li><li>Diaz-Gomez, C., Villalba, J. M., Perez-Vicente, R., Crane, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbate+Stabilization+Is+Stimulated+in+rho(0)HL-60+Cells+by+CoQ10+Increase+at+the+Plasma+Membrane.">Ascorbate Stabilization Is Stimulated in rho(0)HL-60 Cells by CoQ10 Increase at the Plasma Membrane.</a> Biochem Biophys Res Commun. 234, 79-81 (1997).</li><li>Navarro, 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=Protective+role+of+ubiquinone+in+vitamin+E+and+selenium-deficient+plasma+membranes.">Protective role of ubiquinone in vitamin E and selenium-deficient plasma membranes.</a> Biofactors. 9 (2-4), 163-170 (1999).</li><li>Herst, P. M., Berridge, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+surface+oxygen+consumption:+a+major+contributor+to+cellular+oxygen+consumption+in+glycolytic+cancer+cell+lines.">Cell surface oxygen consumption: a major contributor to cellular oxygen consumption in glycolytic cancer cell lines.</a> Biochim Biophys Acta. 1767 (2), 170-177 (2007).</li><li>Baoutina, A., Dean, R. T., Jessup, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trans-plasma+membrane+electron+transport+induces+macrophage-mediated+low+density+lipoprotein+oxidation.">Trans-plasma membrane electron transport induces macrophage-mediated low density lipoprotein oxidation.</a> FASEB J. 15 (9), 1580-1582 (2001).</li><li>Furukawa, 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=Increased+oxidative+stress+in+obesity+and+its+impact+on+metabolic+syndrome.">Increased oxidative stress in obesity and its impact on metabolic syndrome.</a> J Clin Invest. 114 (12), 1752-1761 (2004).</li><li>Del Principe, D., Avigliano, L., Savini, I., Catani, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trans-plasma+membrane+electron+transport+in+mammals:+functional+significance+in+health+and+disease.">Trans-plasma membrane electron transport in mammals: functional significance in health and disease.</a> Antioxid Redox Signal. 14 (11), 2289-2318 (2011).</li><li>Berridge, M. V., Tan, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Capacity+Redox+Control+at+the+Plasma+Membrane+of+Mammalian+Cells+Trans-Membrane,+Cell+Surface,+and+Serum+NADH-Oxidases.">High-Capacity Redox Control at the Plasma Membrane of Mammalian Cells Trans-Membrane, Cell Surface, and Serum NADH-Oxidases.</a> Antioxidants &amp; Redox Signaling. 2 (2), 231-242 (2000).</li><li>Ishiyama, M., Shiga, M., Sasamoto, K., Mizoguchi, M., He, P. 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+New+Sulfonated+Tetrazolium+Salt+That+Produces+a+Highly+Water-Soluble+Formazan+Dye.">A New Sulfonated Tetrazolium Salt That Produces a Highly Water-Soluble Formazan Dye.</a> Chemical &amp; Pharmaceutical Bulletin. 41 (6), 1118-1122 (1993).</li><li>Berridge, M. V., Herst, P. M., Tan, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tetrazolium+dyes+as+tools+in+cell+biology:+New+insights+into+their+cellular+reduction.">Tetrazolium dyes as tools in cell biology: New insights into their cellular reduction.</a> Biotechnology Annual Review. 11, 127-152 (2005).</li><li>Gurtoo, H. L., Johns, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+interaction+of+the+electron+acceptor+2,6-dichlorophenolindophenol+with+bovine+milk+xanthine+oxidase.">On the interaction of the electron acceptor 2,6-dichlorophenolindophenol with bovine milk xanthine oxidase.</a> J Biol Chem. 246 (2), 286-293 (1971).</li><li>Tan, A. S., Berridge, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+trans-plasma+membrane+redox+pathways+reduce+cell-impermeable+dyes+in+HeLa+cells.">Distinct trans-plasma membrane redox pathways reduce cell-impermeable dyes in HeLa cells.</a> Redox Rep. 9 (6), 302-306 (2004).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> R: A language and environment for statistical computing. , (2013).</li><li>Peskin, A. V., Winterbourn, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microtiter+plate+assay+for+superoxide+dismutase+using+a+water-soluble+tetrazolium+salt+(WST-1).">A microtiter plate assay for superoxide dismutase using a water-soluble tetrazolium salt (WST-1).</a> Clinica Chimica Acta. 293 (1-2), 157-166 (2000).</li><li>Higaki, 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=Oxidative+stress+stimulates+skeletal+muscle+glucose+uptake+through+a+phosphatidylinositol+3-kinase-dependent+pathway.">Oxidative stress stimulates skeletal muscle glucose uptake through a phosphatidylinositol 3-kinase-dependent pathway.</a> Am J Physiol Endocrinol Metab. 294 (E889-E897), (2008).</li><li>Zuagg, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectroscopic+characteristics+and+some+chemical+propertiesof+N-methylphenazinium+methyl+sulfate+(phenazine+methosulfate)+and+pyocyanine+at+the+oxidation+level.">Spectroscopic characteristics and some chemical propertiesof N-methylphenazinium methyl sulfate (phenazine methosulfate) and pyocyanine at the oxidation level.</a> J Biol Chem. 239 (11), 3964-3970 (1964).</li><li>Dayan, J., Dawson, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Substrate+specificity+of+ascorbate+oxidase.">Substrate specificity of ascorbate oxidase.</a> Biochem Biophys Res Commun. 73 (2), 451-458 (1976).</li><li>Bellavite, P., della Bianca, V., Serra, M. C., Papini, E., Rossi, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NADPH+oxidase+of+neurtrophils+forms+superoxide+anion+but+does+not+reduce+cytochrome+c+and+dichlorophenolindophenol.">NADPH oxidase of neurtrophils forms superoxide anion but does not reduce cytochrome c and dichlorophenolindophenol.</a> FEBS. 170 (1), 157-161 (1984).</li><li>Berridge, M. V., Tan, A. S., McCoy, K. D., Wang, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biochemical+and+cellular+basis+of+cell+proliferation+assays+that+use+tetrazolium+salts.">The biochemical and cellular basis of cell proliferation assays that use tetrazolium salts.</a> Biochemica. 4, 15-20 (1996).</li><li>Tan, A. S., Berridge, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superoxide+produced+by+activated+neutrophils+efficiently+reduces+the+tetrazolium+salt,+WST-1+to+produce+a+soluble+formazan:+a+simple+colorimetric+assay+for+measuring+respiratory+burst+activation+and+for+screening+anti-inflammatory+agents.">Superoxide produced by activated neutrophils efficiently reduces the tetrazolium salt, WST-1 to produce a soluble formazan: a simple colorimetric assay for measuring respiratory burst activation and for screening anti-inflammatory agents.</a> J Immunol Methods. 238 (1-2), 59-68 (2000).</li><li>Phillips, P. 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=Myricetin+induces+pancreatic+cancer+cell+death+via+the+induction+of+apoptosis+and+inhibition+of+the+phosphatidylinositol+3-kinase+(PI3K)+signaling+pathway.">Myricetin induces pancreatic cancer cell death via the induction of apoptosis and inhibition of the phosphatidylinositol 3-kinase (PI3K) signaling pathway.</a> Cancer Letters. 308 (2), 181-188 (2011).</li><li>Altundag, E., 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=Quercetin-induced+cell+death+in+human+papillary+thyroid+cancer+(B-CPAP)+cells.">Quercetin-induced cell death in human papillary thyroid cancer (B-CPAP) cells.</a> Journal of thyroid research. 2016 (8), (2015).</li><li>Ukeda, H., Kawana, D., Maeda, S., Sawamura, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectrophotometric+Assay+for+Superoxide+Dismutase+Based+on+the+Reduction+of+Highly+Water-soluble+Tetrazolium+Salts+by+Xanthine-Xanthine+Oxidase.">Spectrophotometric Assay for Superoxide Dismutase Based on the Reduction of Highly Water-soluble Tetrazolium Salts by Xanthine-Xanthine Oxidase.</a> Biosci Biotechnol Biochem. 63 (3), 485-488 (1999).</li><li>Halaka, F. G., Babcock, G. T., Dye, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Properties+of+5-methylphenazinium+methyl+sulfate.+Reaction+of+the+oxidized+form+with+NADH+and+of+the+reduced+form+with+oxygen.">Properties of 5-methylphenazinium methyl sulfate. Reaction of the oxidized form with NADH and of the reduced form with oxygen.</a> J Biol Chem. 257 (3), 1458-1461 (1982).</li><li>Maghzal, G. J., Krause, K. H., Stocker, R., Jaquet, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+reactive+oxygen+species+derived+from+the+family+of+NOX+NADPH+oxidases.">Detection of reactive oxygen species derived from the family of NOX NADPH oxidases.</a> Free Radic Biol Med. 53 (10), 1903-1918 (2012).</li></ol>

We have presented two methods for utilizing extracellular electron acceptors, WST-1 and DPIP, in spectrophotometric assays to monitor tPMET in C2C12 myotubes. With the growth of cell lines in standard culture procedures and a spectrophotometer plate reader, it is possible to monitor tPMET with these electron acceptors in a simple microplate assay. WST-1 reduction is reproducible from well-to-well within an assay, but there is day-to-day variability. The day-to-day coefficient of variation (CV) utilizing PBS as the buffer...

The ability of purified plasma membranes to reduce electron acceptors has led to the view that the plasma membrane has an inherent redox capacity1. Previously seen in fungi, plants, and animals, tPMET is a process common to multiple organisms2,3,4,5. Specifically, this process has been demonstrated in Saccharomyces cerevisiae, carrot cells, erythrocytes, lymphocytes, osteosarcoma, melanoma, macrophages, skeletal muscle, and neutrophils2,3,4,5,6,7. In a process that transports electrons across the plasma membrane to reduce extracellular oxidants, tPMET is involved in many cellular functions including: cell growth5,8, cell viability9, iron metabolism10, cell signaling11,12,13, and protection from reactive oxygen species12,14,15. Due to tPMET&#39;s involvement in many cellular functions, an imbalance of tPMET has been hypothesized to contribute to the development of some serious health conditions, including cancer16, cardiovascular disease17, and metabolic syndrome18.
There are multiple ways to monitor the transfer of electrons across the plasma membrane, but the most widely used technique is to assess the reduction of extracellular electron acceptors through colorimetric assays. Commonly used extracellular electron acceptors are tetrazolium salts, DPIP, FeCN, and ferricytochrome c19,20. The most commonly used tetrazolium salt is a second-generation salt known as WST-119. This compound is easier to utilize in colorimetric assays compared to first generation tetrazolium salts due to two sulfonate groups, which increase its water solubility21. WST-1, in conjunction with the intermediate electron acceptor 1-methoxy-phenazine methosulfate (mPMS), is reduced in two single-electron transfer events. This reduction changes the weakly-colored oxidized form of WST-1 to a more intense, yellow formazan20,22. WST-1 has a high molar extinction coefficient of 37 x 103 M-1cm-1, leading to a high assay sensitivity21,22. DPIP is also utilized as an extracellular electron acceptor to monitor tPMET. It has been shown that DPIP can be reduced extracellularly by tPMET without the aid of intermediate electron acceptors23,24. Due to the lack of intermediate electron acceptors, DPIP can directly pick-up electrons from the plasma membrane, unlike WST-124. Similar to DPIP, FeCN has been shown to be reduced extracellularly to ferrocyanide by tPMET without the aid of intermediate electron acceptors19,24. Unlike WST-1 and DPIP, FeCN has a low molar extinction coefficient leading to a lower assay sensitivity9. Another commonly used extracellular electron acceptor to monitor tPMET is ferricytochrome c. Similar to WST-1, ferricytochrome c reduction increases with the use of intermediate electron acceptor, mPMS22. Unlike WST-1 though, the ferricytochrome c method is less sensitive due to a high background and a low molar extinction coefficient22.
Here we present a method for real-time analysis of tPMET through spectrophotometric assays. The method utilized the extracellular electron acceptors WST-1 and DPIP, as they both have a high molar extinction coefficient while being less expensive compared to the other commonly used extracellular electron acceptors such as ferricytochrome c. We utilized phenazine methosulfate (PMS) instead of mPMS they have a similar chemical makeup and PMS is far less expensive. mPMS is photochemically stable which is an important characteristic for a commercial kit that needs a long shelf life. However, we make PMS fresh for each assay, so stability should not be an issue. We also present a method to evaluate possible enzymatic interactions (see Figure 1) between the extracellular electron acceptor and enzymes that may be utilized to further characterize the process of tPMET. Specifically, the enzymes AO and SOD can be used determine which portion of tPMET is due to ascorbate transport or extracellular superoxide release, two common methods for electrons to be transported across the plasma membrane.

<table>
	<tbody>
		<tr>
			<td>C2C12 myoblasts</td>
			<td>American Type Culture Collection&#160;</td>
			<td>CRL-1772</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s modified eagle&#39;s medium - low glucose</td>
			<td>Sigma</td>
			<td>D6046</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Plex animal serum complex</td>
			<td>Gemini Bio-Products&#160;</td>
			<td>100-602</td>
			<td></td>
		</tr>
		<tr>
			<td>penicillin-streptomycin</td>
			<td>Sigma</td>
			<td>516106</td>
			<td></td>
		</tr>
		<tr>
			<td>horse serum</td>
			<td>Gibco Technologies</td>
			<td>16050-130</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s phosphate buffered saline</td>
			<td>Sigma</td>
			<td>D8537</td>
			<td></td>
		</tr>
		<tr>
			<td>trypsin-EDTA</td>
			<td>Sigma</td>
			<td>T4049</td>
			<td></td>
		</tr>
		<tr>
			<td>15 cm culture dishes</td>
			<td>TPP</td>
			<td>93150</td>
			<td></td>
		</tr>
		<tr>
			<td>96 well culture plates</td>
			<td>TPP</td>
			<td>92096</td>
			<td></td>
		</tr>
		<tr>
			<td>2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium Sodium Salt (WST-1)</td>
			<td>Accela ChemBio&#160; Inc</td>
			<td>SY016315</td>
			<td></td>
		</tr>
		<tr>
			<td>phenazine methosulfate&#160;</td>
			<td>Sigma</td>
			<td>P9625</td>
			<td></td>
		</tr>
		<tr>
			<td>L-ascorbic acid</td>
			<td>Sigma</td>
			<td>A5960</td>
			<td></td>
		</tr>
		<tr>
			<td>ascorbate oxidase&#160;</td>
			<td>Sigma</td>
			<td>A0157</td>
			<td></td>
		</tr>
		<tr>
			<td>superoxide dismutase&#160;</td>
			<td>Sigma</td>
			<td>S5395</td>
			<td></td>
		</tr>
		<tr>
			<td>2,6-dichloroindophenol sodium salt&#160;</td>
			<td>ICN Biomedicals</td>
			<td>215011825</td>
			<td></td>
		</tr>
		<tr>
			<td>D-(+)-glucose</td>
			<td>Sigma</td>
			<td>G7528</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES sodium salt</td>
			<td>Sigma</td>
			<td>H3784</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium chloride</td>
			<td>Sigma</td>
			<td>S7653</td>
			<td></td>
		</tr>
		<tr>
			<td>potassium chloride</td>
			<td>Fisher Scientific&#160;</td>
			<td>BP366</td>
			<td></td>
		</tr>
		<tr>
			<td>magnesium sulfate heptahydrate</td>
			<td>Sigma</td>
			<td>M5921</td>
			<td></td>
		</tr>
		<tr>
			<td>calcium chloride dihydrate</td>
			<td>Sigma</td>
			<td>C7902</td>
			<td></td>
		</tr>
		<tr>
			<td>potassium phosphate</td>
			<td>Fisher Scientific&#160;</td>
			<td>BP363</td>
			<td></td>
		</tr>
		<tr>
			<td>Pierce BCA Protein Assay Kit</td>
			<td>Thermo Scientific</td>
			<td>23225</td>
			<td></td>
		</tr>
		<tr>
			<td>Powerwave X-I spectrophotometer</td>
			<td>Biotek Insturments</td>
			<td>discontinued&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectronic Genesys 5 Spectrophotometer</td>
			<td>Thermo Scientific</td>
			<td>336001</td>
			<td></td>
		</tr>
		<tr>
			<td>PureGrade 96-well microplate, F-bottom, clear, untreated, non-sterile</td>
			<td>MidSci</td>
			<td>781602</td>
			<td></td>
		</tr>
		<tr>
			<td>Iron (II) chloride tetrahydrate</td>
			<td>Sigma</td>
			<td>220299</td>
			<td></td>
		</tr>
		<tr>
			<td>Iron (II) sulfate heptahydrate</td>
			<td>Sigma</td>
			<td>215422</td>
			<td></td>
		</tr>
		<tr>
			<td>hypoxanthine</td>
			<td>Sigma</td>
			<td>H9636</td>
			<td></td>
		</tr>
		<tr>
			<td>xanthine oxidase</td>
			<td>Sigma</td>
			<td>X4500</td>
			<td></td>
		</tr>
		<tr>
			<td>Excel</td>
			<td>Microsoft</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>R Studio</td>
			<td>Rstudio</td>
			<td></td>
			<td>https://www.rstudio.com/products/rstudio/</td>
		</tr>
		<tr>
			<td>KC4</td>
			<td>Biotek Insturments</td>
			<td>discontinued&#160;</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring trans-plasma membrane electron transport by c2c12 myotubes

Trans-plasma membrane electron transport (tPMET) plays a role in protection of cells from intracellular reductive stress as well as protection from damage by extracellular oxidants. This process of transporting electrons from intracellular reductants to extracellular oxidants is not well defined. Here we present spectrophotometric assays by C2C12 myotubes to monitor tPMET utilizing the extracellular electron acceptors: water-soluble tetrazolium salt-1 (WST-1) and 2,6-dichlorophenolindophenol (DPIP or DCIP). Through reduction of these electron acceptors, we are able to monitor this process in a real-time analysis. With the addition of enzymes such as ascorbate oxidase (AO) and superoxide dismutase (SOD) to the assays, we can determine which portion of tPMET is due to ascorbate export or superoxide production, respectively. While WST-1 was shown to produce stable results with low background, DPIP was able to be re-oxidized after the addition of AO and SOD, which was demonstrated with spectrophotometric analysis. This method demonstrates a real-time, multi-well, quick spectrophotometric assay with advantages over other methods used to monitor tPMET, such as ferricyanide (FeCN) and ferricytochrome c reduction.

Statistics were performed with ANOVA with repeated measures using RStudio statistical software25. Sample sizes are indicated in the figure legends.
To monitor tPMET, C2C12 myotubes were utilized along with extracellular electron acceptors, WST-1 and DPIP. AO was used to determine which portion of WST-1 and DPIP reduction was due to ascorbate efflux and SOD was used to determine which portion of WST-1 redu...

Watch this Scientific Journal Video about Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes at JoVE.com

Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes

The goal of this protocol is to spectrophotometrically monitor trans-plasma membrane electron transport utilizing extracellular electron acceptors and to analyze enzymatic interactions that may occur with these extracellular electron acceptors.

Trans-plasma membrane electron transport (tPMET) plays a role in protection of cells from intracellular reductive stress as well as protection from damage ...

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