Mediation of Aldosterone Induced Anti-Natriuresis via RNA-Synthesis de novo.

Abstract

The adrenocortical hormone aldosterone (0.34 [mu]g/kg) or its vehicle was given to saline loaded (0.9% NaCl, 17 [mu]g/kg, subcutaneously) male rats which had been adrenalectomized 5 days earlier. Orotic acid 6-C14, 3 [mu]curies/100 g body weight, was given intravenously to each rat. Urine was collected for periods of 1, 1 1/2 or 2 hr. and analyzed for Na. Kidneys were removed, homogenized and the microsomal fraction obtained. RNA was extracted from this fraction and the incorporation of orotic acid 6-Cl4 used to determine RNA-synthesis de novo. It was found that aldosterone increased the microsomal level of RNA at about the time it enhanced Na reabsorption. The lack of effect of aldosterone on Na reabsorption before an increase in RNA-synthesis could be detected is consistent with the hypothesis that this hormone mediates its antinatriuretic action, in vivo, via DNA directed synthesis of RNA.