Role of angiotensin and adrenoceptors in hemodynamic response to aortic cross-clamping.

Academic Article

Abstract

  • An earlier study has shown that angiotensin and catecholamines were responsible for the vasoconstriction observed in the isolated hindlimb preparation during aortic cross-clamping. That study also demonstrated that when vasoconstriction was blocked with an alpha-adrenergic antagonist, phenoxybenzamine, vasodilation was elicited by aortic cross-clamping. The present study tested the hypothesis that this vasodilation was mediated via beta-adrenergic receptors. Eighteen dogs had their hindlimb denervated, vascularly isolated, and pump perfused with blood drained from the inferior vena cava, after passing through a gas-exchanging membrane where oxygen and carbon dioxide tensions were normalized. Left and right thoracotomies were performed, and the aorta and inferior vena cava were cross-clamped. The cross-clamping was associated with 29-37% increase in limb vascular resistance in control dogs (n = 6), in animals pretreated with propranolol (2 mg/kg, n = 6), and in dogs pretreated with a combination of phenoxybenzamine (3 mg/kg) and propranolol (2 mg/kg, n = 6). In animals pretreated with a combination of phenoxybenzamine, propranolol, and enalaprilat (2 mg/kg, n = 6), an angiotensin-converting enzyme inhibitor, limb vascular resistance did not change. This study has confirmed that aortic cross-clamping is associated with vasoconstriction induced by angiotensin and activation of alpha-adrenoceptors and has further demonstrated that vasodilation is attributable to beta-adrenoceptor activation.
  • Authors

    Published In

    Keywords

  • Angiotensin II, Animals, Aorta, Catecholamines, Constriction, Dogs, Enalaprilat, Hemodynamics, Hindlimb, Osmolar Concentration, Receptors, Adrenergic, Sympatholytics, Vascular Resistance
  • Digital Object Identifier (doi)

    Author List

  • Gelman S; Curtis SE; Bradley WE; Henderson CT; Parks DA; Cain SM
  • Start Page

  • H14
  • End Page

  • H20
  • Volume

  • 264
  • Issue

  • 1 Pt 2