The degradation of proteins in pinniped skeletal muscle: viability of post-mortem tissue in physiological research.

As marine divers, pinnipeds have a high capacity for exercise at depth while holding their breath. With finite access to oxygen, these species need to be capable of extended aerobic exercise and conservation of energy. Pinnipeds must deal with common physiological hurdles, such as hypoxia, exhaustion and acidosis, that are common to all exercising mammals.

Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris).

Northern elephant seals (Mirounga angustirostris) (NES) are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia, and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature.