| AIM: During excessive physical exercise and labor, the oxygen and blood demand of myocardium increase acutely while the blood flowing in coronary arteries is relatively deficient. Consequently, the relative myocardium ischemia and the relative myocardium ischemia/reperfusion (rI/R) injury occurred. Accordingly it is necessary to elucidate the mechanism and the protective measures against the rI/R injury. So, in order to verify the delayed protection of exercise preconditioning (EP) against the rI/R injury and explore the role of heme oxygenase-1 in EP, the study as follows were carried out. METHODS: 1) Five models were established, including the EP model induced by the 4-times short-time excessive physical exercise, the rI/R model induced by exercise in vivo experiment, the myocardial rl/R model induced by the weak current stimulus in vitro experiment, the myocardial cell ischemic preconditioning model and the myocardial cell I/R model in cellular experiment. 2) In order to test the delayed protection of EP against the rI/R injury, the third grade grade loading exercise time, the cardiac function parameter and the levels of MDA in serum or in coronary effluent were detected. 3) To explore the role of HO-1 in the delayed protection of EP against the rl/R injury, the HO-1 inhibitor (ZnPP) and the HO-1 inductor (hemin) were administered. In addition, these following indexes besides that in part 2, including the activity of HO-1 in myocardium, the content of COHb in venous blood and in culture medium, the cell survival rate and the content of Ca2+ in myocardial cell, were also detected RESULT: 1) The MDA in serum and in coronary effluent increased significantly after the rI/R while the recovery rate of cardiac function decreased distinctly. When the EP was performed 24 hours before the rI/R, the third grade grade loading exercise time and the recovery rate of cardiac function increased markedly, while the MDA in serum and...
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