Endothelin-1 enhances the secretory capacity of the regenerating rat adrenal cortex, acting via the B receptor subtype

摘要

Many lines of evidence indicate that endothelins (ET) stimulate the growth and secretory activity of the adrenal cortex, acting via the specific receptor subtypes A and B (ETA and ETB). The present investigation aimed to ascertain whether ET-1 affects the secretory capacity of the regenerating rat adrenal cortex. Rats underwent left adrenal enucleation and contralateral adrenalectomy, and were decapitated 4, 6 or 8 days after surgery. Groups of animals were given two subcutaneous injection of 2 nmol/kg ET-1, 24 and 12 h before the sacrifice. Plasma aldosterone and corticosterone concentrations rose in relation to the number of days of regeneration, and ET-1 significantly increased them over the respective control value. The stimulatory effect of ET-1 at day 8 of adrenal regeneration was blocked by the simultaneous administration of the ETB receptor antagonist BQ-788 (3 nmol/kg), but not of the selective ETA receptor antagonist BQ-123. When administered alone the two antagonists were ineffective. These findings suggest that ET-1 enhances the secretory capacity of regenerating rat adrenals, acting through the ETB receptor subtype.