[Effect of temperature in vivo and in vitro on oxidation and phosphorylation in the myocardial mitochondria of white rats].

Respiration and phosphorylation were studied on isolated myocardial mitochondria of intact and acute and chronic cold-exposed rats at 25 and 15 degrees C. The data obtained attest to activation of oxidation and phosphorylation of rat myocardial mitochondria in response to cold exposure of different duration and power at constant parameters of energy coupling. Cold adaptation changed the mitochondrial response to short-term hypothermia and subsequent warming up. As the temperature in vitro was reduced, the rates of respiration and phosphorylation diminished, with phosphorylation exhibiting a greater temperature sensitivity than respiration.