One hour of myocardial ischemia in conscious dogs increases β-adrenergic receptors, but decreases adenylate cyclase activity

Dorothy E. Vatner*, Delvin R. Knight, You Tang Shen, John X. Thomas, Charles J. Homcy, Stephen F. Vatner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

An increased myocardial β-adrenergic receptor density has been reported following myocardial ischemia. However, it is not clear whether these receptors are effectively coupled to adenylate cyclase which would be necessary for enhanced physiological responsiveness. We, therefore, examined the effects of myocardial ischemia in six conscious dogs (4 intact and 2 with posterior wall denervation) in which the left circumflex coronary artery was occluded. Ischemia was verified by measurement of regional blood flow by radioactive microspheres. After 1 h of coronary artery occlusion, the dogs were anesthetized with pentobarbital and the left ventricle was divided into normal, intermediate and ischemic regions. A crude membrane fraction was prepared from each region. β-Adrenergic receptors were quantitated with 125I-cyanopidolol binding and adenylate cyclase activity was measured. In all, six animals studied, β-adrenergic receptor density increased progressively and adenylate cyclase activity decreased progressively, when the ischemic myocardium was compared to the intermediate and the non-ischemic myocardium. Since adenylate cyclase activity declined, these results do not support the concept that the increased β-receptor density induced by myocardial ischemia is causally related to enhanced β-adrenergic sensitivity.

Original languageEnglish (US)
Pages (from-to)75-82
Number of pages8
JournalJournal of Molecular and Cellular Cardiology
Volume20
Issue number1
DOIs
StatePublished - Jan 1 1988

Keywords

  • Adenylate cyclase
  • Coronary artery occlusion
  • Ischemia
  • Micropheres
  • β-Adrenergic receptors

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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