Modulacion De Aldosterona

Modulation of Plasma Aldosterone Concentration by Plasma Potassium in Anephric Man in the Absence of a Change in Potassium Balance
C. ROBERT COOKE, JOHN S. HORVATH, MICHAEL A. MOORE, TURNER BLEDSOE, and W. GORDON WALKER
From the Department of Medicine, The Johns Hopkins Hospital and The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205

A B S T R A C T In studies on sevenanephric patients, (1-5). It is still uncertain, however, whether the moduglucose and insulin administration before hemodialysis lating effect of potassium is dependent upon gross produced a significant reduction in plasma potassium changes in potassium balance or whether it may also concentration (mean reduction = 1.3, 1.7, and 1.4 meq/ occur in response to changes in plasma potassium conliterat 60, 120, and 180 min, respectively) which was centration independently of changes in potassium balaccompanied by a significant and sustained reduction in ance. Large changes in aldosterone secretion were obplasma aldosterone concentration. There was a signifi- served by Cannon, Ames, and Laragh in association with cant correlation between plasma aldosterone and plasma changes in potassiumbalance that were accompanied by potassium concentration (r = +0.74, P < 0.001) and be- relatively minor variations in plasma potassium concentween changes in the concentration of plasma aldosterone tration (6). Since plasma potassium concentration per se occurring in individual patients and the corresponding appeared to be a poor determinant of aldosterone sechanges in plasma potassium concentration (r= +0.52, cretory activity in these studies, these investigators posP < 0.01). There was no significant change in plasma tulated that aldosterone secretion may be regulated by sodium concentration, and plasma corticoid concentra- variations in zona glomerulosa potassium accumulation tion, which was monitored as an index of ACTH elabo- resulting from cumulative changes in potassium balance. ration,was reduced at 60 min but increased subsequently However, studies by Dluhy, Axelrod, Underwood, and as symptoms attributable to hypoglycemia were observed. Williams have shown that plasma aldosterone concenThese studies demonstrate that plasma aldosterone tration can be increased acutely by intravenous potasconcentration can be modulated acutely by transitory sium administration regardless of theprevious dietary changes in plasma potassium concentration without a potassium intake (7). Similarly, aldosterone secretion change in potassium balance. The effect of glucose and by the isolated adrenals of dogs (3) and sheep (8) can insulin administration on intracellular potassium in the be stimulated acutely by direct intra-arterial potassium adrenal cortex is uncertain, and although increasednet administration. While these observations suggest that movement of potassium into cells is the presumptive aldosterone secretion is indeed responsive to abrupt inmechanism of the reduction in plasma potassium concen- crements in plasma potassium concentration, they do not tration, whether the potassium content of the adrenal specifically answer the question of whether changes in cortex mayhave increased or decreased or remained es- plasma potassium concentration, decreases as well as insentially unchanged, cannot be inferred from our data. creases, may alter aldosterone secretion in the absence of a change in potassium balance. Previous studies on anephric patients have indicated INTRODUCTION that aldosterone secretion may be regulated predominantly Previous studies have shown thataldosterone production by potassium in the absence of the renin-angiotensin syscan be markedly influenced by changes in potassium tem (9, 10). To determine whether changes in plasma potassium concentration may alter aldosterone secretion Received for publication 19 April 1973 and in revised in anephric patients in the absence of a change in potassium balance, we administered glucose and insulin...