Effects of Increases in Plasma Vasopressin Concentration on Plasma Renin Activity, Blood Pressure, Heart Rate, and Plasma Corticosteroid Concentration in Conscious Dogs*

Abstract

It is known that vasopressin decreases PRA and heart rate and increases blood pressure and plasma corticosteroid concentration. The purpose of this study was to determine the plasma concentration of vasopressin required to produce these effects. Arginine vasopressin was administered iv to five normal conscious dogs as priming injections of 0.1, 0.5, 1.0, 2.5, 5.0, and 10.0 ng/kg, followed by infusions of 0.01, 0.05, 0.1, 0.25, 0.5, and 1.0 ng/kg x min, respectively, for 30 min. These doses produced increases in the plasma vasopressin concentration (+/- SE) of 1.0 +/- 0.8, 2.1 +/- 4.3, 4.3 +/- 1.8, 11.4 +/- 1.0, 19.7 +/- 6.4, and 30.8 +/- 7.8 pg/ml, respectively, from a basal level of 2.7 +/- 0.2 pg/ml. An increase in the plasma vasopressin concentration of 2.1 +/- 0.3 pg/ml suppressed PRA by 19 +/- 5% (P < 0.02); increases of 4.2 +/- 1.8 pg/ml or more suppressed PRA by 34 +/- 12% (P < 0.005). Only the highest dose of vasopressin produced a significant pressor effect (9 +/- 3 mm Hg; P < 0.05) or lowered the heart rate (18 +/- 4 beats/min; P < 0.005). An increase in plasma vasopressin concentration of 19.7 +/- 6.4 pg/ml was required to increase the plasma corticosteroid concentration (1.2 +/- 0.2 to 2.2 +/- 0.4 microgram/dl; P < 0.01); the largest dose of vasopressin increased the plasma corticosteroid concentration from 1.5 +/- 0.1 to 2.4 +/- 0.6 microgram/dl (P < 0.02). Twenty-four-hour water deprivation in the same dogs increased the plasma vasopressin concentration from 2.5 +/- 0.2 to 7.4 +/- 0.6 pg/ml (P < 0.01). Nonhypotensive hemorrhage in another group of dogs increased the plasma vasopressin concentration from 2.5 +/- 0.2 to 47.4 +/- 16.8 pg/ml (P < 0.05). These data indicate that elevations in the plasma vasopressin concentration within the range observed during 24 h of water deprivation and nonhypotensive hemorrhage produced significant decreases in renin secretion and heart rate and elevations in blood pressure and corticosteroid secretion.

Effect of methadone on plasma arginine vasopressin level and urine production in conscious dogs

“…In agreement with investigations which incorporated extensive circulatory monitoring, the relative bradycardia can be at least partially accounted for by the increased AVP level (Malayan et al, 1980;Montani et al, 1980;Liard et al, 1981;Undesser et al, 1985). These reports show that when plasma AVP levels are increased to an extent comparable with the levels reached in this experiment, there is an increase in total peripheral resistance without concurrent increase in mean arterial pressure.…”

Characteristics of the Receptors Which Mediate the Stimulation of ACTH Secretion by Vasopressin in Conscious Dogs

“…The changes in corticosteroid concentration were small as was expected from previous experiments with infu sions of physiologically relevant doses of vasopressin in conscious dogs (10]. The change in plasma AC'TH concen tration required to increase plasma corticosteroid concen tration by I 2 pg/dl is far less likely to be detected by AC'TH radioiummunoassy.…”

Vasopressin-mediated forearm vasodilation in normal humans. Evidence for a vascular vasopressin V2 receptor.

“…The potent vasoconstrictor effect of arginine vasopressin has been demonstrated in vitro (2) and during high dose infusion in animals (21,(36)(37)(38). In humans, however, only modest increases in blood pressure or systemic vascular resistance occur during AVP infusion (22,31,32).…”

“…AVP directly augments nerve terminal release of norepinephrine (8), but also causes withdrawal of sympathetic tone via sensitization of baroreflexes (9)(10)(11)(12)(13)(14). Other evidence suggests additional mechanisms that might contribute to an AVP-mediated vasodilator effect; AVP increases release of vasodilator prostaglandins in vitro and in animals (15)(16)(17), causes release of endothelium-dependent relaxant factor(s) (18), and decreases renin secretion (19)(20)(21)(22).…”