Effect of zinc ion on myocardial mitochondrial protection / 中国药学杂志

ABSTRACT

OBJECTIVE: To investigate the cardioprotective effect of exogenous zinc (Zn2+) on the mitochondrial pathway, and to explore its possible mechanism. METHODS: Rat heart tissue-derived H9c2 cardiac cells were cultured, and then randomly divided into control group, ZnCl2 group (1-20 μmol·L-1, 20 min), ZnCl2 plus inhibitor group [PI3K inhibitor LY294002, 10 μmol·L-1and mitochondrial ATP sensitive potassium channel (mKATP) inhibitor 5-HD, 0.5 mmol·L-1, inhibitors treated cells for 10 min and then ZnCl2 20 min] and inhibitor group (10 min). The mitochondrial permeability transition pore (mPTP) opening was evaluated by measuring mitochondrial membrane potential (ΔΨm). Tetramethylrhodamine ethyl ester (TMRE) diacetate fluorescence images were obtained with laser scanning confocal microscopy. GSK-3β and AKT phosphorylation were determined with Western blot. The cells were subjected to simulated ischemia/reperfusion injury, cell viability were determined with flow cytometry. Cells were transfected with constitutively active GSK-3β-S9A (GSK-3β-S9A) plasmid by Fugene 6 transfection kit, mPTP opening was evaluated by confocal microscopy. RESULTS: Compared with the normal, exposure of cells to H2O2 for 20 min caused a marked decrease in TMRE fluorescence, treatment of cells with different dose of Zn2+ prevented the loss of TMRE fluorescence caused by H2O2 with the peak at 10 μmol·L-1. Western blot showed that Zn2+ significantly enhanced the GSK-3β and AKT phosphorylation, the effect that was significantly reversed by LY294002, but not 5-HD. Compared with the normal, ischemia/reperfusion markedly reduced cell viability. Zn2+ applied at ischemia did not increase the cell viability, but significantly increased the cell viability when given at reperfusion. Zn2+ could mimic the specific mPTP inhibitor cyclosporin A (1 μmol·L-1) and prevent the mPTP opening, which was again reversed by LY294002 but not 5-HD. Zn2+ was not able to exert protection in cells transfected with the GSK-30-S9A. CONCLUSION: Zn2+ can induce myocardial mitochondrial protective effect by modulating the mPTP opening through the inactivation of GSK-3β via PI3K/AKT pathway. mKATP may not be involved in the action of Zn2+.