Vasopressin reduces cardiac function and augments cardiopulmonary baroreflex resistance increases in man.

Abstract

We examined the effects of physiologic infusions of arginine vasopressin (AVP) on cardiovascular hemodynamics and on reflex responses initiated by decreasing cardiopulmonary baroreceptor stimulation (with lower body negative pressure) in 10 healthy, captopril-pretreated young men (19-27 yr). Their responses were compared with those of four volunteers given isosmotic infusion. Heart rate, stroke volume, blood pressure, and forearm blood flow were measured by electrocardiography, impedance cardiography, radial artery cannulation, and strain gauge plethysmography. Two 55-min infusions of AVP at rates of 0.15 and 0.40 ng/kg per min increased average plasma concentrations from control levels of 5 pg/ml to 18 and 36 pg/ml, respectively. These infusions resulted in progressive reductions of heart rate and cardiac output and increases of forearm and total peripheral resistance. Blood pressure increases were significant only during the larger AVP infusion rate. Lower body negative pressure provoked reflex increases of total peripheral resistance. These increases were enhanced 60% during AVP infusion compared with increases during control (pre-AVP). Baseline measurements and reflex responses were unchanged by isosmotic infusions. These results demonstrate that AVP has profound effects on cardiovascular function and augments cardiopulmonary baroreflex-mediated increases of peripheral resistance in man.

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

“…In humans, however, only modest increases in blood pressure or systemic vascular resistance occur during AVP infusion (22,31,32). Intravenous administration of AVP increases FBF (32).…”

“…22 normal volunteers, 13 males and 9 females, were studied in three protocols. The age of the subjects was 26±5 yr (mean±SD), ranging from 19 to 34 yr. All subjects underwent a screening medical history, physical examination, and laboratory testing, which included complete blood count, serum electrolytes, blood glucose, serum trans-aminases, blood urea nitrogen, and serum creatinine, to exclude cardiac, renal, or hepatic disease.…”

“…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).…”

Vasopressin dysregulation: Hyponatremia, fluid retention and congestive heart failure

“…In a study of 10 normotensive adult volunteers, infused AVP augmented forearm vascular resistance and total peripheral resistance in the presence of decreased cardiopulmonary baroreceptor stimulation caused by lower body negative pressure [27]. Arterial baroreceptors were not affected, since the heart rate did not change before and after the AVP infusion.…”

Stimulated Secretion of Arginine Vasopressin during Hemodialysis in Patients with Hemodialysis Hypotension

“…In the 5 patients, each plasma AVP level reached maximally up to 74.0 ± 22.5% during HD from the respective basal level, with a 31.4 ± 6.0% increase in SVR was observed at this time. In normal subjects, an approximately 260% increase in AVP is reported with an increase in SVR by approximately only 20% [6]. Thus, it is indicated that there might be an elevated sensitivity to the vasoconstrictive action of AVP in these patients, and that the secreted AVP exerted a substantial effect on the increase in SVR.…”