Role of V1 receptors in the action of vasopressin on the baroreflex control of heart rate

J. Luk, I. Ajaelo, V. Wong, J. Wong, D. Chang, L. Chou, I. A. Reid

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

Arginine vasopressin (AVP) elicits a larger decrease in heart rate for a given increase in arterial pressure than do other vasoconstrictors, but there is disagreement as to whether this results from an increase in baroreflex gain or a resetting of the baroreflex to a lower blood pressure. It is also unclear which type of vasopressin receptor mediates the action of vasopressin on the baroreflex. In the present study, the effects of vasopressin, selective vasopressin V1 and V2 receptor agonists, oxytocin, and a vasopressin V1 receptor antagonist on the baroreflex control of heart rate were investigated in conscious, chronically prepared rabbits. Baroreflex curves were generated with intravenous infusions of phenylephrine and nitroprusside and analyzed using a four-parameter logistic model. Intravenous infusion of vasopressin at 5 ng · kg-1 · min-1 increased mean arterial pressure by 9 mmHg and decreased heart rate by 31 beats/min. The arterial pressure at the midrange of the baroreflex curve (BP50) decreased from 75.9 ± 4.8 to 57.6 ± 1.7 mmHg (P < 0.01), indicating a shift of the baroreflex curve to a lower pressure, but the gain did not change significantly. The actions of vasopressin on blood pressure, heart rate, and BP50 were completely blocked by pretreatment with d(CH2)5[Tyr(Me)2]AVP, a selective V1 receptor antagonist. Infusion of [Phe2,Ile3,Orn8]AVP, a selective V1 receptor agonist, produced cardiovascular effects similar to those of vasopressin and decreased the BP50 of the baroreflex from 73.0 ± 2.2 to 63.8 ± 2.2 mmHg (P < 0.05). Neither deamino-[D-Arg8]AVP (DDAVP), a selective V2 receptor agonist, nor oxytocin significantly altered blood pressure and heart rate or the BP50 of the baroreflex. These results provide evidence that infusion of vasopressin in conscious rabbits resets the baroreflex control of heart rate to a lower pressure without increasing its gain and demonstrate that this action is mediated by vasopressin V1 receptors.

Original languageEnglish (US)
Pages (from-to)R524-R529
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume265
Issue number3 34-3
StatePublished - Jan 1 1993

Keywords

  • V receptors
  • baroreflex resetting
  • blood pressure
  • oxytocin
  • rabbit
  • vasopressin antagonist

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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