Neurons in area postrema mediate vasopressin-induced enhancement of the baroreflex

B. F. Cox, M. Hay, V. S. Bishop

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Intravenous infusion of arginine vasopressin (AVP) has been shown to enhance baroreflex sensitivity, and this enhancement is dependent on the integrity of the area postrema. However, previous studies did not differentiate a role for cell bodies in the area postrema vs. the dense network of fibers located in and around the lateral and ventral margins of this circumventricular organ. In the present study, baroreflex function was assessed in conscious rabbits by examining heart rate after ramp infusions of phenylephrine (PE) and AVP. The subsequent day, the excitotoxin kainic acid was injected (30 nl initially, with five 15-nl supplemental injections of a 1 ng/nl solution over 1 h) into the area postrema, thus selectively destroying cell bodies. After an 8-day recovery period, baroreflex function was again assessed. The bradycardic response to graded infusion of PE (slope = -2.29 ± 0.30) was not significantly different after selective lesions of area postrema neurons (slope = -1.88 ± 0.49). In contrast, the previously enhanced bradycardic response to infusion of AVP (slope = -5.76 ± 1.02) was significantly attenuated (slope = -2.31 ± 0.21) to levels similar to that seen with infusion of PE. Thus selective chemical lesions of area postrema neurons block vasopressin-induced enhancement of the baroreflex.

Original languageEnglish (US)
Pages (from-to)H1943-H1946
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume258
Issue number6 27-6
DOIs
StatePublished - 1990
Externally publishedYes

Keywords

  • arterial pressure
  • dose-response
  • kainic acid
  • phenylephrine
  • rabbits

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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