Amrinone preconditioning in the isolated perfused rabbit heart

Abstract

Background. Ischemic preconditioning (IPC) reduces infarct size in experimental preparations. IPC, however, is not without detrimental effects. We studied amrinone as a possible alternative to IPC. Methods. Isolated perfused rabbit hearts were given a 5-minute infusion of 10 μmol/L amrinone followed by a 5-minute washout (n = 6). The anterior descending artery was then occluded for 1 hour and reperfused for 1 hour. Six hearts underwent IPC, with two episodes of 5-minute global ischemia followed by 5-minute reperfusion before LAD occlusion; eight control hearts received no preconditioning. Left ventricular pressure and ischemic zone epicardial monophasic action potentials were continuously monitored. Results. IPC but not amrinone reduced peak pressure before anterior descending artery occlusion. Peak pressure fell significantly during ischemia and reperfusion in all hearts. End diastolic pressure rose significantly during reperfusion in control and IPC hearts but not in amrinone hearts. Action potentials shortened during ischemia in all hearts. They returned to preocclusion values in control hearts but lasted beyond preocclusion values in IPC and amrinone hearts. Both the incidences of ventricular fibrillation and infarct size were significantly reduced in amrinone hearts but not in IPC hearts. Conclusions. Amrinone is not only a useful inotropic agent but is also a superior preconditioning agent when compared to IPC.