Calcitonin gene-related peptide enhances the recovery of contractile function in stunned myocardium

Introduction: Calcitonin gene-related peptide, a potent vasodilating inotro pic agent, increases coronary artery perfusion when administered exogenousl y and reduces ischemic injury in nonmyocardial tissue. However, it is uncle ar whether this agent improves recovery of myocardial performance after rev ersible myocardial ischemia. Methods: Nine dogs underwent complete occlusion of the left anterior descen ding coronary artery for 15 minutes and were monitored during 24 hours of r eperfusion. Calcitonin gene-related peptide (0.07 mu g . kg(-1) . min(-1)), nitroglycerin (65 mu g . kg(-1) . min(-1)), or saline solution placebo was infused intravenously during initial reperfusion. Ischemia/reperfusion was repeated in concurrent 24-hour periods until all animals received infusion s in random order. Micromanometry and sonomicrometry determined left ventri cular pressure and myocardial segment length. Myocardial performance, based on the linear relationship between stroke work and end-diastolic segment l ength, was estimated with the preload recruitable work area. Results were a nalyzed as percent control and compared statistically with the use of repea ted measures analysis of variance. Results: Recovery of myocardial performance was augmented during reperfusio n with calcitonin gene-related peptide infusion relative to placebo (P = .0 05; mean preload recruitable work area +/- SE after calcitonin gene-related peptide infusion, 2484 +/- 705 mm Hg at 90 minutes of reperfusion versus 1 473 +/- 300 mm Hg for placebo. Recovery of performance after nitroglycerin infusion was similar to recovery after placebo. Conclusions: Calcitonin gene-related peptide infusion improves recovery of contractile function in stunned myocardium. Unlike inotropic agents that im pair recovery from reversible ischemia, calcitonin gene-related peptide may confer cardioprotective effects on ischemic myocardium.