Regulation of pH in human skeletal muscle: adaptations to physical activity.

Regulation of pH in skeletal muscle is the sum of mechanisms involved in maintaining intracellular pH within the normal range. Aspects of pH regulation in human skeletal muscle have been studied with various techniques from analysis of membrane proteins, microdialysis, and the nuclear magnetic resonance technique to exercise experiments including blood sampling and muscle biopsies. The present review characterizes the cellular buffering system as well as the most important membrane transport systems involved (Na(+)/H(+) exchange, Na-bicarbonate co-transport and lactate/H(+) co-transport) and describes the contribution of each transport system in pH regulation at rest and during muscle activity. It is reported that the mechanisms involved in pH regulation can undergo adaptational changes in association with physical activity and that these changes are of functional importance.