OBJECTIVETo determine the protective effect of pomegranate polyphenols on cardiac function in rats with myocardial ischemia/reperfusion (I/R) injury and explore the possible mechanism.

METHODSFifty SD rats were randomized into 5 equal groups, including a sham-operated group, an I/R model group, and 3 pomegranate polyphenol dose groups (150, 300, and 600 mg/kg). The rats were subject to a 45-min left main coronary artery occlusion followed by a 180-min reperfusion to induce myocardial I/R injury except for the rats those in the sham-operated group. The cardiac functions were monitored continuously during the experiment. At the end of the reperfusion, arterial blood samples were obtained to measure plasma contents of lactate dehydrogenase (LDH), creatine kinase (CK), malondialdehyde (MDA) and the activities of superoxide dismutase (SOD). Triphenyltetrazolium chloride (TTC) staining was used to evaluate the infarct size.

RESULTSCompared with the sham-operated group, all the rats with I/R showed significantly decreased left ventricular systolic pressure (LVSP), maximal rates of increase/decrease of the left ventricular pressure (±dp/dtmax) (P<0.01) and significantly increased left ventricular end-diastolic pressure (LVEDP) (P<0.01). Compared with the I/R model group, all the 3 pomegranate polyphenol groups had significantly improved cardiac function (P<0.05), decreased plasma contents of CK, LDH and MDA (P<0.01), increased SOD activities (P<0.01), and obviously reduced infarct size (P<0.01).

CONCLUSIONPomegranate polyphenols can protect the cardiac function of rats with I/R injury probably in association with their actions in enhancing oxygen free radical scavenging activity and decreasing lipid peroxidative damage of the myocardial tissues.