Effects of potassium and rubidium on muscle cell bicarbonate

A tissue CO2 content method was used to study the effects of Rb and K on skeletal muscle bicarbonate and pH in rats. Intraperitoneal injection of large loads of RbCl or KCl in normal rats produced extracellular acidosis and a transient intracellular alkalosis in muscle (and also in renal cortex). This supports previous suggestions that rapid exchange of administered cation for intracellular hydrogen occurs. In K-deficient alkalotic rats, loading with RbCl or KCl caused a greater fall in extracellular bicarbonate but a smaller rise in muscle bicarbonate. Muscle bicarbonate was unchanged by the alkalosis of K depletion or the reduction in extracellular bicarbonate resulting from chronic feeding of Rb. After the acute RbCl and KCl loads, repair of intracellular alkalosis occurred within 6 hr, associated with a transient sharp rise in tissue citrate content. It is suggested that production of citrate and other metabolic acids may play a role in stabilizing cellular acid-base balance.