Calcium uptake and storage in isolated heart mitochondria influenced by sodium and potassium ions.
With rising concentrations of KCl the rate of Ca2+ uptake was moderately increased by 37 percent. NaCl induced a strong decrease of the rate of Ca2+ uptake from 498 to 194 nmoles of Ca2+ per sec-gm of protein (0-100 mM NAaCl). Elevating the K+/Na+ quotient from 0.1 to 15.7, we found a concomitant alteration of the rate of Ca2+ uptake which is mediated exclusively by sodium ions. These data indicate that with lowering of the K+/Na+ gradient there is a marked diminution of the mitochondrial rate of Ca2+ uptake and Ca storage. Our findings may contribute to answering how Na+-K+ exchange at the cell membrane may influence intracellular Ca2+ binding and Ca2+ turnover.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002474:Cell-Free System; D007700:Kinetics; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D011188:Potassium / Q000494:pharmacology*; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology*
D012964:Sodium; D011188:Potassium; D002118:Calcium