MECHANISMS OF HEMODYNAMIC CONTROL OF SECRETION OF ALDOSTERONE IN THE DOG

Changes in aldosterone and cortisol secretions were measured in response to constriction of the thoracic inferior vena cava and of the carotid arteries in intact and nephrectomized dogs. Aldosterone and cortisol secretions increased and decreased normally in response to caval constriction and release in nephrectomized animals. Carotid constriction in intact animals increased aldosterone secretion to the same extent as caval constriction, but without increasing cortisol secretion. Cortisol secretion rose after carotid constriction in vagotomized dogs. Nephrectomy led to transient low rates of aldosterone secretion in otherwise intact animals and prevented the increase of aldosterone secretion following carotid constriction in most, but not all, animals in which there was no evidence for ACTH release. Since carotid constriction decreases renin secretion, this effect of nephrectomy is probably independent of the renin-angiotensin system. The data suggest the presence of a mechanism involving the central nervous system, not mediated through ACTH release or the renin-angiotensin system, which is important in the physiologic control of aldosterone secretion, and which may involve an inhibitor of aldosterone secretion.