Hormonal modulation of atrial natriuretic factor receptors and effects on adrenal glomerulosa cells of female rats.

This study was done to determine if a decrease in the aldosterone-suppressant effect of atrial natriuretic factor (ANF) by progesterone and an increase by estrogen was caused by modulation of adrenal zona glomerulosa ANF receptors. Freshly dispersed glomerulosa cells from virgin, 13-15 day pregnant, ovariectomized (OVX) estradiol-17 beta-treated and OVX progesterone-treated rats were used. Competitive displacement of specifically bound [125I]ANF1-28 with unlabelled ANF1-28 yielded concentrations of guanylate cyclase-linked ANF-R1 plus ANF-R2 (clearance) receptors and the displacement with unlabelled ANF4-23 yielded ANF-R2 receptors; the difference between the two was treated as the concentration of ANF-R1 receptors.

Inhibition of the aldosterone-suppressant activity of atrial natriuretic factor by progesterone and pregnancy in rats.

Angiotensin II (AII) caused concentration-dependent increase in aldosterone secretion by dispersed zona glomerulosa cells from non-ovariectomized (non-OVX) and ovariectomized (OVX) rats treated with the vehicle (peanut oil), beta-estradiol (0.1 mg/kg/d x 3) or progesterone (2 mg/kg/d x 3); this effect of AII was greater on cells from progesterone- than from estrogen-treated animals. In contrast, atrial natriuretic factor (ANF) was 100- to 1,000-fold less effective in suppressing AII-stimulated aldosterone production by cells from progesterone-treated (both non-OVX and OVX) and pregnant (17-20 day) rats than by cells from nonpregnant controls and estrogen-treated animals.