Membrane excitability and calcium homeostasis in exercising skeletal muscle.

Abstract

Preservation of the membrane electrochemical gradients for Na, K, and Ca is vital to the maintenance of skeletal muscle structure and function. Muscle excitability may be depressed during contractile activity by changes in the gradients for Na and K, while muscle force may be reduced by an activity-induced increase in free intracellular Ca. Compensatory processes help to maintain ion electrochemical gradients in normal, active muscles, but compensatory mechanisms may be impaired in injured or diseased muscles, contributing to muscle pathology.