Effects of sodium depletion and angiotensin II on osmotic regulation of vasopressin

Effects of sodium depletion and angiotensin II on osmotic regu-lation of vasopressin. Am. J. Physiol. 250 (Regulatory Integra-tive Comp. Physiol. 19): R287-R291, 1986.-After alterations in sodium balance, osmotic reactivity of vasopressin (AVP) release was evaluated in seven conscious dogs during bilateral intracarotid infusions of hypertonic saline, A low-sodium diet reduced plasma sodium concentration by 3%; deoxycorticoster-one acetate (30 mg/day for 2 days) elevated the concentration by 1%. Neither treatment altered resting plasma AVP. Hyper-tonic intracarotid infusions increased jugular plasma osmolality by 20 t 2 mosmol/kg independent of manipulations. Plasma AVP values were significantly increased (P < 0.05) in sodium-depleted dogs compared with values of the control animals. In addition, the osmotic reactivity of AVP release was evaluated during exogenous administration of angiotensin II (ANG II). Intravenous infusion of ANC II (5 ng- kg-‘. min-‘) increased plasma concentration of ANG II but did not alter concentration of plasma AVP. The slope for the relationship of jugular plasma osmolality to plasma AVP during hypertonic intracarotid in-fusions was significantly increased with intravenous infusion of ANG II. Sodium depletion and intravenous ANC II poten-tiate the relationship of plasma osmolality and plasma AVP when evaluated with intracarotid hypertonic saline infusions in dogs. dogs; antidiuretic hormone; deoxycorticosterone acetate TONICITY and volume of extracellular fluid (ECF) are major physiological factors that regulate secretion of vasopressin (18). Plasma osmolality has been shown to regulate plasma arginine vasopressin (AVP) concentra-tion in a linear fashion above a threshold (17, 22). Re-ductions in ECF volume (blood volume specifically) re-sult in an exponential increase in concentration of AV