[Protective effects of endogenous carbon monoxide against myocardial ischemia-reperfusion injury in rats]

The present study is aimed to explore the effects of endogenous carbon monoxide on the ischemia-reperfusion in rats. Wistar rats were intraperitoneally injected with protoporphyrin cobalt chloride (CoPP, an endogenous carbon monoxide agonist, 5 mg/kg), zinc protoporphyrin (ZnPP, an endogenous carbon monoxide inhibitor, 5 mg/kg) or saline. Twenty-four hours after injection, the myocardial ischemia-reperfusion model was made by Langendorff isolated cardiac perfusion system, and cardiac function parameters were collected. Myocardial cGMP content was measured by ELISA, and the endogenous carbon monoxide in plasma and myocardial enzymes in perfusate at 10 min after reperfusion were measured by colorimetry. The results showed that before ischemia the cardiac functions of CoPP, ZnPP and control groups were stable, and there were no significant differences. After reperfusion, cardiac functions had significant differences among the three groups (P < 0.05). Compared with pre-ischemia, the cardiac function decreased and obvious cardiac arrest was shown in control and ZnPP groups, while the cardiac function in CoPP group did not change significantly, maintaining a relatively stable level. At the same time, three groups' carbon monoxide level, myocardial enzymology and the cardiac function recovery time after reperfusion also had significant differences (P < 0.05). Compared with those in control group, recovery after reperfusion was faster, activities of creatine kinase and lactic dehydrogenase were significantly decreased, plasma CO and myocardial cGMP contents were significantly increased in CoPP group, while these changes were completely opposite in ZnPP group. It is concluded that endogenous carbon monoxide can maintain cardiac function, shorten the time of cardiac function recovery, and play a protective role in cardiac ischemia-reperfusion.