Effect of Simultaneous Potassium and Saline Loading on Plasma Aldosterone Levels

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Abstract
To assess the relative importance of the renin-angiotensin system and K in the acute regulation of aldosterone secretion in the salt depleted state, normal subjects were infused with an isotonic saline solution containing KC and the responses compared to the infusions of isotonic saline (500 ml/h) and KCL alone (20 meq K+/h). Subjects were studied recumbent in balance on a 10 meq Na/100 meq K diet. The rates of infusing saline and K were selected to produce comparable but opposite effects on the levels of plasma aldosterone. As plasma renin activity (PRA) declined and plasma K increased during the combined saline-KCl infusions, plasma aldosterone levels appeared to be the arithmetic sum of the changes in these parameters. In fact, the calculated changes in aldosterone levels per unit change in PRA or K from each infusion alone, correlated well with the observed levels, further supporting an additive relationship. These data support the concept that in the salt depleted state the renin-angiotensin system and K are equally important in the acute regulation of plasma levels of aldosterone.
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