Fast effects of aldosterone on electrolytes in human lymphocytes are mediated by the sodium-proton-exchanger of the cell membrane.

An in vitro effect of aldosterone on intracellular sodium, potassium and calcium concentrations and cell volume was shown in human mononuclear leukocytes (HML). In the present paper the effect of aldosterone on propionate-induced swelling of HML and, thereby, the Na+/H+-exchanger of the cell membrane was investigated. Aldosterone in physiological concentrations stimulated the cell swelling from 3 min on significantly. This effect had to be attributed to an increased activity of the Na+/H+-exchanger since amiloride blocked it almost completely. The inhibitor of protein synthesis actinomycin D prevented this action, cortisol had an intermediate effect. These data are the first to identify the Na+/H+-exchanger as a primary target of mineralocorticoid action in HML.