Regulation of the Na,K-ATPase: Special implications for cardiovascular complications of metabolic syndrome.

Skeletal muscle contains one of the largest pools of Na,K-ATPase in the body, and therefore plays a central role in the clearance of [K(+)] from the blood during the ingestion or infusion of K(+). In the case of major hyperkalaemia (i.e. pathological increase of plasma [K(+)]), skeletal muscle can rapidly accumulate significant amounts (up to 50%) of extracellular K(+). Thus, skeletal muscle is an important temporary storage for K(+). Hyperkalaemia and impaired K(+)-tolerance frequently occurs in people who present features of the metabolic syndrome, concomitant with impaired activity of the sodium pump and decreased expression of the Na,K-ATPase subunits. These pathological conditions may lead to membrane depolarization in excitable tissues and to the development of cardiac arrhythmia or other cardiovascular complications that are a major consequence of metabolic syndrome. Thus, increasing Na,K-ATPase activity in skeletal muscle may protect from these complications.