Impaired endothelium-dependent relaxation after coronary reperfusion injury: Evidence for G-protein dysfunction

Paulo R.B. Evora, Paul J. Pearson, Hartzell V. Schaff

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


This study was done to determine whether abnormal receptor-dependent release of endothelium-derived relaxing factor (EDRF) might be caused by G-protein dysfunction. Dogs were exposed to global myocardial ischemia (45 minutes, induced by aortic cross-clamping) followed by reperfusion (60 minutes) while on cardiopulmonary bypass, and coronary arteries were then studied in vitro in organ chamber experiments. After reperfusion, endothelium-dependent relaxation to the receptor-dependent agonists adenosine diphosphate and acetylcholine was significantly impaired as well as to sodium fluoride, which acts on a pertussis toxin-sensitive G-protein. In contrast, endothelium-dependent relaxations to the receptor-independent agonists A23187 and phospholipase C were normal. Furthermore, endothelium-dependent relaxation to poly-l-arginine (molecular weight, 139,200), which appears to induce endothelium-dependent relaxation of the canine coronary artery by a nonnitric oxide pathway, waa unaffected by ischemia and reperfusion. These experiments suggest that global myocardial ischemia and reperfusion selectively impair receptor-mediated release of EDRF (nitric oxide) but that the ability of the endothelial cell to produce EDRF or generate endothelium-dependent relaxation to nonnitric oxide-dependent agonists remains intact. We hypothesize that coronary reperfusion injury lead to G-protein dysfunction in the endothelium.

Original languageEnglish (US)
Pages (from-to)1550-1556
Number of pages7
JournalThe Annals of thoracic surgery
Issue number6
StatePublished - Jun 1994

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine


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