1. The respiration rate of rat liver mitochondria was stimulated by up to 70% when the extramitochondrial Ca2+ concentration was raised from 103 to 820 nM. This occurred when pyruvate, 2-oxoglutarate, or threo-(Ds)-isocitrate was employed as substrate, but not when succinate was used. 2. Ruthenium Red prevented the stimulation of mitochondrial respiration by extramitochondrial Ca2+, showing that the effect required Ca2+ uptake into the mitochondrial matrix. 3. Starvation of rats for 48 h abolished the stimulation of mitochondrial respiration by extramitochondrial Ca2+ when pyruvate was used as substrate, but did not affect the stimulation of 2-oxoglutarate oxidation by extramitochondrial Ca2+. 4. Our findings are in accord with proposals that oxidative metabolism in liver mitochondria may be stimulated by Ca2+ activation of intramitochondrial dehydrogenases.
Stimulation of the respiration rate of rat liver mitochondria by sub-micromolar concentrations of extramitochondrial Ca2+
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J D Johnston, M D Brand; Stimulation of the respiration rate of rat liver mitochondria by sub-micromolar concentrations of extramitochondrial Ca2+. Biochem J 1 July 1987; 245 (1): 217–222. doi: https://doi.org/10.1042/bj2450217
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