Energy Sources in Hibernator Heart: Pyridine Nucleotide Metabolism

Summary Homogenates prepared from the hearts of hibernating and cold-exposed nonhibernating ground squirrels (Citellus trede-cemlineatus) have been studied with respect to the metabolism of both oxidized and reduced forms of pyridine nucleotide coenzymes in the presence of fluoride and glucose-6-phosphate. The rates of oxygen comsumption by preparations from nonhibernating animals were highest with the oxidized forms of the coenzymes. By contrast, the rates of oxygen consumption by heart homogenates from hibernating animals were highest with the reduced forms. It is postulated that these findings indicate the operation of a cyclic lipid metabolism in the heart of hibernating animals that does not operate or is depressed in the aroused state.