Abstract: Objective To study the effects of rapamycin(RAPA) on sevoflurane preconditioning during myocardial ischemia/reperfusion(I/R) in rats. Methods Thirty-six healthy adult male Wistar rats, 250 g-280 g, were randomly divided into three groups(n=12): group I/R, group sevoflurane preconditioning(group S+I/R), group sevoflurane preconditioning plus RAPA(group S+I/R+RAPA). The hearts were excised and perfused in a langendorff apparatus. The left ventricular diastolic pressure(LVEDP), left ventricular developed pressure(LVDP), the maximum rate of increase or decrease of left ventricular pressure(±dp/dtmax), heart rate(HR) were recorded at 30 min of equilibrium and 120 min of reperfusion respectively. Myocardial infarct size and lactate dehydrogenase(LDH) levels were examined by 2,3,5-triphenyltetrazolium chloride(TTC) staining and enzyme standard method at 120 min of reperfusion. Expressions of microtubule-associated protein 1 light 3 (LC3), target of rapamycin (mTOR), phosphorylated mTOR(p-mTOR) were determined by Western blotting. Results After reperfusion, compared with that in group I/R, the cardiac function in group S+I/R was improved(P<0.05), the myocardial infarct size[(47±6)%,(29±5)%], LDH levels[(29±5) U/L,(19±4) U/L] and the expressions of LC3-Ⅱwere decreased(P<0.05), while the expression of p-mTOR increased in group S+I/R(P<0.05). Compared with that in group S+I/R, the cardiac function in group S+I/R+RAPA was worse(P<0.05), the myocardial infarct size[(29±5)%,(46±3)%], LDH levels[(19±4) U/L,(27±5) U/L] and the expressions of LC3-Ⅱwere increased(P<0.05), while the expression of p-mTOR decreased (P<0.05) in group S+I/R+RAPA(P<0.05). Conclusions Rapamycin could decrease the protective effective of sevoflurane preconditioning and may be related to p-mTOR and autophagy.
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