Regulation of the aldosterone secretion in the frog Rana esculenta L

Abstract

The concentration of aldosterone in plasma of the frog Rana esculenta L. has been measured by radioimmunoassay without chromatography. In the normal frogs, the concentration of this steroid is 0.82 ± 0.16 μg/100 ml in the plasma of blood removed by heart puncture. Using daily administration of metopirone or aminoglutethimide, the steroid is no more detectable after six injections. Hypophysectomy produces, 15 days after the operation, a small but significant diminution of the hormone concentration. On the contrary, one administration of synthetic 1–24ACTH, or extract of frog kidney, produces an elevation of the aldosterone level, not only in the normal, but also in the hypophysectomized frogs. These results suggest that, in the amphibians, the aldosterone level depends on the renin-angiotensin system and pituitary ACTH. On the other hand, the injection of corticosterone into normal frogs produces a significant decrease of aldosterone concentration, which suggests feedback mechanisms in the control of aldosterone secretion.