Effects of phentolamine and propranolol on the changes in vascular capacitance and resistance caused by the carotid sinus baroreflex

K. Shigemi, M. J. Brunner, A. A. Shoukas

Research output: Contribution to journalConference article

Abstract

We examined the contribution of α and β adrenergic receptor mechanisms to the changes in systemic vascular capacitance and resistance caused by the carotid sinus baroreflex in anesthetized vagotomized dogs. The carotid sinuses were isolated from the systemic circulation and perfused with controlled pressures. A constant flow cardiopulmonary bypass preparation was used in which the change in external reservoir volume was continuously measured. The change in vascular capacitance was determined from the changes in arterial compliance, venous compliance, and the reservoir volume when carotid sinus pressure was reduced from 200 to 50 mmHg without any receptor antagonist, with either α(phentolamine) or β(propranolol) antagonist, and with both α and β antagonists. The change in vascular capacitance was 25 ± 10 ml/kg with no antagonist. The capacitance change was reduced by 74% with pentolamine, by 33% with propranolol, and by 75% with both antagonists. Vascular resistance was increased by 0.60 ± 0.21 (from 0.72 ± 0.16 to 1.34 ± 0.27) mmHg·min·kg/ml when carotid sinus pressure was decreased under control condition. The resistance change was reduced by 80% with phentolamine, increased by 20% with propranolol, and reduced by 60% with both antagonists. These results suggest that capacitance and resistance vessels are predominantly activated by α receptors.

Original languageEnglish (US)
Number of pages1
JournalAnnals of biomedical engineering
Volume19
Issue number5
StatePublished - Dec 1 1991
Event1991 Annual Fall Meeting of the Biomedical Engineering Society - Charlottesville, VA, USA
Duration: Oct 12 1991Oct 14 1991

ASJC Scopus subject areas

  • Biomedical Engineering

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