Aldosterone and Sodium Conservation: The Effect of Acute Dietary Sodium Deprivation on the Plasma Concentration, the Metabolic Clearance and the Secretion and Excretion Rates of Aldosterone in Normal Subjects1

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Abstract
The effect of dietary sodium deprivation on the metabolic clearance, metabolic rate constants, volumes of distribution, and disappearance rate of administered radioactive aldosterone as well as on the secretion and excretion rates and plasma concentration of aldosterone was studied in healthy subjects. Aldosterone secretion and excretion rates and the calculated plasma aldosterone concentration increased during the period of dietary sodium restriction. Using a 2-compartmental model system, results derived from analyses of the disappearance curves of tritiated aldosterone in plasma both before and during dietary sodium restriction did not reveal a change in the distribution volumes, the metabolic rate constants, or the metabolic clearance of aldosterone. Under the conditions of these studies the increase in plasma aldosterone concentration during dietary sodium deprivation was determined by the elevated rate of aldosterone secretion rather than by changes in the metabolic clearance of aldosterone. The investigations again indicated that in some subjects the sodium retaining mechanisms are extremely sensitive to acute dietary sodium deprivation, and that the degree of negative sodium balance per se is not a critical factor in initiating renal sodium conservation or in attaining either aldosterone hypersecretion or maximal renal sodium conservation. In addition, the data again provide evidence that the rate of aldosterone secretion per se is not a critical factor in initiating sodium conservation.