Experimental study on myocardial protection by adjunct use of carperitide (hANP) in cardiac surgery.

BACKGROUND In recent years, various beneficial roles of human atrial natriuretic peptide (hANP) have been demonstrated in the internal medicine and surgical fields. However, direct myocardial protection by hANP against myocardial ischemic reperfusion injury has been rarely investigated. Thus, we investigated it from aspects of cardiac surgery. METHODS Twenty-four pigs underwent extracorporeal circulation and were divided into three groups: control group (treated with only cardioplegic solution after aorta clamping; cardioplegic arrest for 30 minutes followed by reperfusion for 60 minutes); low dose group (treated with cardioplegic solution and ANP (25 microg)); and high dose group (treated with cardioplegic solution and ANP (100 microg)). Blood and myocardial cGMP, myocardial Ca and ATP concentration were determined. Histological examinations were performed using an electron microscope. RESULTS Blood and myocardial cGMP and myocardial ATP levels were significantly higher in the hANP treatment groups than the control group. Myocardial Ca concentrations were significantly lower in the hANP treatment groups than the control group. In electron microscopy, ischemic reperfusion injury was rarely observed in the hANP treatment groups. CONCLUSION The study demonstrated that hANP improves ischemic reperfusion injury and suggested that hANP exerts direct myocardial protection against myocardial injury associated with cardiac surgery (cardioplegic arrest while cardiopulmonary bypass).