Potassium depletion: effects on intracellular pH and electrolyte distribution in skeletal and cardiac muscle.

Abstract

SummaryAn experiment was designed to study in the rat the effects of dietary potassium depletion on skeletal and cardiac muscle, with particular reference to changes in potassium and hydrogen ion gradients across the cell membranes. A fall in plasma potassium content was accompanied by a considerable reduction in the potassium content of skeletal muscle, but only a small fall in the potassium content of cardiac muscle. However, the rise in the potassium ion gradient in cardiac muscle was twice that in skeletal muscle.The potassium‐depleted rats showed an extracellular alkalosis, but the intracellular pH of skeletal muscle (measured with 14C‐labelled 5,5‐dimethyl‐2,4‐oxazolidinedione) fell. There was no significant relationship between the intracellular pH and potassium content of cardiac muscle, but the rise in potassium ion gradient was accompanied by a fall in intracellular pH and a rise in the hydrogen ion gradient. Significant curvilinear relationships were found between potassium and hydrogen ion gradients across skeletal and cardiac muscle cell membranes.It is suggested that changes in the potassium ion gradient, with accompanying changes in the hydrogen ion gradient, play a more important part than changes in potassium content, in causing disturbances of cardiac rhythm. In potassium depletion, the fall in the intracellular pH of skeletal muscle, and the relationship between potassium and hydrogen ion gradients, may be due to reduced efficiency of the process responsible for the active extrusion of hydrogen ions from the cell.