OBJECTIVETo study comparatively the effect of Guanxin II and its constituents, including Salvia, Red Peony root, Chuanxiong, Safflower and Dalbergia wood, in scavenging active oxygen free radical (OFR) to explore their mechanism in overcoming the experimental acute ischemic myocardial injury and protecting myocardial tissue.

METHODSThe experimental acute myocardial ischemic model was established by intraperitoneal injection of pituitrin to rats. OFR level in animal heart tissue was directly measured with low-temperature electron paramagnetic resonance (EPR) spectrometer.

RESULTSThe pathological examination of HE stained slide of myocardial tissue and electrocardiography of model animal showed that typical changes of acute myocardial ischemia occurred in myocardial tissue, EPR showed that OFR level in myocardial tissue increased abnormally. The ethanol extract of Guanxin II and its constituents could lower the increased OFR level close to normal, thus to alleviate the myocardial damage.

CONCLUSIONOverproduction of OFR could induce damage of heart tissue, its level could be measured directly using low temperature EPR. One of the molecular mechanisms of Guanxin II and its constituents in antagonizing and repairing myocardial damage is to scavenge the abnormal increased active OFR in tissue. This study has provided a basis for further studying the mechanism of Chinese composite recipes and their constituents.