Studies of relationship between angiotensin II and potassium ions on aldosterone release.

Abstract

The effects of angiotensin [A] II on dog glomerulosa Na-K-ATPase activity, transmembrane cation active transport and aldosterone [ALDO] production were examined. Na-K-ATPase activity of glomerulosa homogenate and plasma membrane fraction were determined and compared to activities in the presence of AII. AII had no effect on Na-K-ATPase activity. To determine whether the lack of effect of AII on the enzyme was not due to the experimental conditions, the effect on monovalent cation active transport was measured. The presence of AII caused a slight and insignificant reduction of active 86Rb uptake in vitro by glomerulosa slices, and passive 86Rb+ uptake was not affected. However, increasing amounts of ouabain had a parallel inhibitory effect on the steroidogenic stimulus of A and on the intracellular K concentration. The cardiac glycoside not only blocked A stimulation of ALDO production, but also the effects of c[cyclic]AMP stimulation. Intracellular K is evidently important in regulating ALDO production, even though the mechanism of action of AII could not be related to the influx of K into the glomerulosa cells.