The sequestration of Ca2+ by mitochondria in rat heart cells.
Rat heart ventricular cells, purified by Percoll density gradient centrifugation, were incubated in the presence of 1.3 mM CaCl2. After 20 min incubation, samples of the cells were lysed in medium containing 0.3 mM digitonin, ruthenium red and EGTA, and a mitochondrial fraction was isolated at intervals thereafter. Extrapolation of the mitochondrial 45Ca2+ contents to zero time enabled the endogenous 45Ca2+ to be estimated at the time of cell lysis. The lysis conditions yielded essentially complete release of lactate dehydrogenase from the cells, but caused negligible damage to the mitochondria as judged by their retention of glutamate dehydrogenase, and their ability to accumulate and retain Ca2+ in the absence of ruthenium red and EGTA. The data indicate that about 13% of total cell Ca2+ only may be mitochondrial in vivo.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002414:Cations, Monovalent / Q000378:metabolism; D002458:Cell Fractionation; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002414:Cations, Monovalent; D007770:L-Lactate Dehydrogenase; D005969:Glutamate Dehydrogenase; D003576:Electron Transport Complex IV; D002118:Calcium