| Objective To investigate the protective effect of L-carnitine on myocardial ischemia-reperfusion injury in rats .Methods all harvested isolated hearts were perfused on Langendorff apparatus with oxygenized K-H solution for 20 min. The hearts were then exposed to ischemia for 30 min. Following the ischemia the hearts were reperfused with K-H solution for 120 min to serve as the control group A. Either 5 or 10 mmol/L of L-carnitine were added into the K-H solution for 20 min at the beginning of reperfusion to generate group B and group C, respectively. The derivatives of the intraventricular pressure curve (DP/DT), left ventricular developed pressure (LVDP), and coronary flux were monitored during the entire experiment. The levels of ATP, hepatin, malondialdehyde (MDA), and superoxide dismutase (SOD) in tissue, and lactic dehydrogenase (LDH), creatine phosphate kinase (CPK), malondialdehyde (MDA), and superoxide dismutase (SOD) concentration in the coronary efflux were all measured. Myocardial tissue specimens from all groups were examined for ultrastructural evidence of myocardial ischemia-reperfusion injury by scanning electron microscope.Results Compared with the control group, the treatment with L-carnitine yielded better results . DP/DTmax and LVDP were higher( P <0.01). At the same time, the levels of ATP and SOD were all elevated( P <0.01),while the hapatin was preserved in the tissue( P <0.05). However, the concentration of MDA, CPK and LDH was all reduced( P <0.01). Ultrastructures were preserved in treatment groups.Conclusion L-carnitine shows a protective effect against ischemia-reperfusion injury, which is partly due to its prevention of energy loss and its antioxidant activity.
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