Abstract: Objective: To probe into changes of the cardiomyocyte apoptotic index and to observe the effect of recombinant human growth hormone(rGH) on cardiomyocyte apoptosis and mitochondria at different times after ischemicreperfusion(IR). Methods: Seventy-eight Wistar rats were randomly allocated into the IR group, the IR+rGHⅠgroup, the IR+rGHⅡ group and a sham operation group( without I/R injury). The IR group was given a normal sodium solution subcutaneously each night for 7 days before the experiment; the IR+GHⅠgroup was subcutaneously given 0.75U/kg recombinant human growth hormone each night for 7 days before the experiment; the IR+GHⅡgroup was given 1U/kg recombinant human growth hormone 30 seconds prior to ischemia. TUNEL was used to detect cardiomyocyte apoptosis. Results: The apoptosis cells appeared after 2 hours of reperfusion, increasing to a zenith after 24 hours of reperfusion and then decreasing. The difference of the apoptosis index between the IR group and the IR+rGHⅠ group was statistically significant(P＜0.05), however, that between the IR group and the IR+rGHⅡ group was not. Conclusions: Recombinant growth hormone, used for 7 days before ischemicreperfusion can reduce the number of apoptosis cells and attenuate the damage to mitochondria, however, used 30 seconds prior to ischemia it does not have this effect.

Key words: Myocardial reperfusion injury, Apoptosis, Recombinant growth hormone, Rat, Wistar