THE EFFECT OF ALDOSTERONE ON ELECTROLYTES IN MUSCLE, KIDNEY CORTEX, AND SERUM

Abstract

This investigation was carried out on 128 young rats maintained on diets varying in sodium and potassium content. For all experiments the rats were divided into at least three groups: intact, adrenalectomized (ADX), and ADX given dl-aldosterone (10 or 25 μg) daily for 5 days. In rats on a normal diet serum Na fell from 151 to 134 meq/l. and serum K rose from 7 to 11 meq/l. as a result of adrenalectomy; muscle Na decreased from 119 to 97 meq/kg dry weight and muscle K increased somewhat. In general, kidney cortex Na and K changed in the same direction as the muscle cations. On all high-Na diets muscle Na increased in ADX rats while serum Na remained constant. Tissue K changes were somewhat more variable than alterations in tissue Na. The principal finding was that the administration of aldosterone prevented most of the tissue cation changes caused by adrenalectomy regardless of their direction. Thus a dual control of tissue electrolytes by the hormone is suggested, namely that aldosterone might control tissue cation concentrations indirectly through its influence on plasma levels, and also directly by inhibiting the cellular sodium pump.