Muscle metabolic profiles and fiber-type composition in some marine mammals

1. Hexokinase, lactate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, and malate dehydrogenase activities as well as fiber type composition were determined in skeletal muscles of the California sea lion (Zalophus californianus), the sea otter (Enhydra lutris), and the Pacific white-sided dolphin (Lagenorhynchus obliquidens). 2. The subcutaneous muscle of the sea lion had intermediate glycolytic and oxidative enzyme activities. 3. The locomotory muscles examined in the otter and porpoise did not contain a single predominant fiber type, but did have a well developed oxidative as well as glycolytic metabolic capacity.