Endothelin-A receptor antagonist BQ123 protects against myocardial and endothelial reperfusion injury

Background: This study was designed to investigate the effects of the selective endothelin-A receptor antagonist BQ123 on myocardial and endothelial function after reversible deep hypothermic ischemia and reperfusion. Methods: Isogenic intra-abdominal heterotopic heart transplantation was performed in Lewis rats. After one hour of cold ischemic preservation reperfusion was started after application of either saline vehicle or BQ123 (1 mu mol/L). Left-ventricular pressure-volume relations and myocardial blood flow were assessed after one and 24 hours of reperfusion. Responses to endothelium-dependent vasodilator acetylcholine and endothelium-independent vasodilator sodium nitroprusside were also determined, Results: BQ123 significantly improved myocardial contractility, as indicated by the leftward shift of the systolic pressure-volume relation and significantly increased myocardial blood flow during early reperfusion (p < 0.05). Although myocardial function and baseline myocardial blood flow were similar in both groups after 24 hours of reperfusion, endothelium-dependent vasodilatation was still significantly higher in the BQ123 group (p(0.05). Conclusions: These results suggest that endothelin-A receptor antagonists may be useful in reducing ischemia/reperfusion injury after heart transplantation by preservation of myocardial and endothelial function.