THE EGTA - ruthenium red quench technique was used to obtain initial-velocity plots of Ca2+ uptake by skeletal-muscle mitochondria. The Km was 5 μM and the Hill coefficient 1.9 at both 0° and 10°C. Inorganic phosphate stimulated and Mg2+ inhibited initial rates of transport. In experiments on Ca2+ release, the Na+ Ca2+ exchange was demonstrated. Factors influencing Ca2+ release during anaerobiosis include phosphate concentration and extent of Ca2+ loading. The results are discussed in relation to the possible participation of mitochondria in the calcium-ion regulation of muscle.
Bibliographical noteFunding Information:
This research was supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin. We are grateful to Dr. Marion Greaser for helpful advice and constructive criticism, and to Oscar Mayer and Company for the supply of muscles. Muscle Biology Manuscript #l40.