Effect of sodium deficiency on beta-melanocyte-stimulating hormone stimulation of aldosterone in isolated rat adrenal cells.

Abstract

The effect of sodium deficiency on the adrenal sensitivity to beta MSH was studied using collagenase-dispersed rat adrenal cells from rats maintained on a normal sodium or a sodium-deficient diet for 2 weeks. In the cells prepared from adrenals of rats fed a normal sodium diet, angiotensin II (AII) and ACTH caused a dose-dependent increase in aldosterone production by glomerulosa cells at a threshold concentration of 10(-10) M and induced a maximal response at 10(-8) M. beta MSH also stimulated aldosterone production at a threshold of 10(-8) M and a maximum at 10(-6) M. However, in the cells from sodium-depleted rats, the threshold for AII was 10(-11) M and the maximum was 10(-8) M, while the threshold for ACTH and beta MSH was 10(-10) M. The shift to the left of the dose-response curve for beta MSH during sodium depletion was greater than that for AII or ACTH. The aldosterone levels obtained with maximal doses of beta MSH and AII were similar during sodium depletion. Sodium depletion did not affect the corticosterone response of decapsular cells to all three stimulators. In conclusion, sodium deficiency enhances the sensitivity of the adrenal glomerulosa cells to beta MSH, causing significant stimulation of aldosterone production by doses of beta MSH within the physiological range. These data suggest that beta MSH or peptides containing beta MSH may play a role in the regulation of aldosterone secretion during sodium deficiency in the rat.