[Mechanism of reciprocal effects of acetylcholine on oxidation of alpha-ketoglutarate and succinate in heart and liver mitochondria. Factors influencing detection of the acetylcholine effect].

Effect of acetylcholine administration (50 mg/100 g) on phosphorylating oxidation in the liver and heart mitochondria of rats and guinea pigs has been studied. The reciprocal effect of acetylcholine on alpha-ketoglutarate and succinate oxidation (acceleration and inhibition, respectively) was observed. In both cases, the ADP/O coefficient increased. The effect was specific for two substrates and was absent when pyruvate, isocitrate, malate and glutamate were oxidized. When a mixture of glutamate and malate was oxidized producing alpha-ketoglutarate by transamination, acetylcholine stimulated respiration and that effect was abolished by aminooxyacetate. The extent of acetylcholine effects depended on the substrate concentration, duration of storage of isolated mitochondria, the type of the tissue and species of an animal. The described increase in oxidative phosphorylation efficiency by acetylcholine administration corresponded to physiological action of the blood and tissue acetylcholine in the organism which promoted saving of oxygen consumption.