pH and hypometabolism in mammalian hibernation

Abstract

In mammalian hibernation, the reduction of metabolic rate occurs by three processes: inhibition of cold-induced thermogenesis, temperature effect on metabolic reaction rates (Q10), and a further inhibition. Concomitantly, the animal undergoes a marked respiratory acidosis (CO2 retention). At the intracellular level, a respiratory acidosis occurs in brain and muscles, suggesting that intracellular pH regulation is depressed. The hyperventilation of early arousal provides evidence for the hypothesis that acidosis exerts an inhibition in hibernation, and should be removed to permit thermogenesis. Muscle glycolysis and brown adipose tissue thermogenesis are depressed by acidosis in vitro, but a decrease in pH probably also affects other systems, especially the preoptic area of the hypothalamus.