Vascular Effects of Arginine-Vasopressin, Angiotensin and Noradrenaline in Adrenal Insufficiency

Abstract

Publisher Summary Non-osmotic release of arginine-vasopressin (AVP) is present in conscious, adrenalectomized animals with either gluco- or mineralocorticoid deficiency. This chapter investigates whether the non-osmotic release of AVP has a vascular effect in the gluco- or mineralocorticoid-deficient state. Administration of a specific inhibitor of the hydroosmotic effect of AVP profoundly improves the capacity of mineralocorticoid- or glucocorticoid-deficient animals to excrete an acute water load. Using a sensitive and potent AVP vascular antagonist, a vascular role of endogenous AVP to maintain mean arterial pressure is observed in adrenal insufficiency in the conscious rat. The effect is more readily demonstrable in the mineralocorticoid- than the glucocorticoid-deficient state. Activation of the renin-angiotensin and sympathetic nervous systems in the mineralocorticoid deficient state also contributes to the maintenance of blood pressure. In the mineralocorticoid-deficient state, antagonism of the renin-angiotensin system or α-adrenergic blockade is associated with prolongation of the hypotensive effect of the AVP vascular antagonist. Thus, AVP, angiotensin II, and adrenergic stimulation all combine to support mean arterial pressure in the mineralocorticoid-deficient, conscious rat.