Abstract
The effect of synthetic alpha-human atrial natriuretic polypeptide (α-hANP) on the in vivo and in vitro release of ACTH and corticosterone was examined. In the in vivo study ACTH and corticosterone responses to rapid 2-ml/rat hemorrhage were measured in sixteen conscious rats after α-hANP administration. The hemorrhage increased plasma ACTH and corticosterone concentrations in the control group of rats (p>0.01). ANP inhibited hemorrhageinduced ACTH secretion (p<0.05), but the plasma corticosterone response was not affected. In the in vitro study a high concentration of ANP (1 μM) reduced basal corticosterone secretion from the isolated rat adrenal gland (p<0.05), but the response to ACTH (10 ng/ml) and dibutyryl cyclic AMP (0.5 mM, 5.0 mM) was not affected. Our data suggest that ANP inhibits hemorrhage-induced ACTH secretion from the anterior pituitary but inhibits corticosterone secretion from the adrenal gland very weakly.
