[Effect of animal serum on mitochondrial respiration in stress]

Effect of small amounts of rat blood serum on respiration of the animal brain mitochondria was studied. The following conditions were shown to be critical: the rats had to be kept undisturbed to avoid the effects of stress, high concentrations of mitochondrial suspension had to be used, incubation of the suspension at 26 degrees and use of succinate as a substrate of oxidation were also essential. Low concentrations of blood serum obtained from rats, maintained in tranquil state and, especially, under conditions of immobilization stress, increased the respiration rate in active state (V3) as well as in inactive state (V4). An increase in concentration of blood serum caused an inhibition of the V3 and activation of the V4 states as well as complete uncoupling of oxidative phosphorylation in mitochondria.