The interaction of calcium transport and ADP phosphorylation in brain mitochondria.
Brain mitochondria respiring on glutamate plus malate had a respiratory control index (RCI) for the addition of ADP of 5.5 and P:O ratio of 2.9. These mitochondria also had a Ca2+:O ratio of approximately 5.2, and the ratio of oxygen uptake in the presence of external Ca2+ to that in its absence was 4.0. The reversible transition of respiration to State 3 on the addition of ADP in phosphate media could be blocked by the prior accumulation of 50--200 nmoles/mg of Ca2+. The inhibition was reversible, and on the release of the accumulated Ca2+ by Na+/Ca2+ exchange, the mitochondria became responsive to ADP. The decreased response to ADP following the addition of Ca2+ is probably associated with Ca2+ ions complexing adenine nucleotides within the mitochondria, thus reducing the exchangeable pool and the amount of ADP available to the F1-ATPase.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D005971:Glutamates / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010766:Phosphorylation; D051381:Rats
D005971:Glutamates; D000244:Adenosine Diphosphate; D002118:Calcium