Relationship between phosphorylation of GSK-3β and high glucose-caused abolition of cardioprotection induced by sevoflurane postconditioning / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between phosphorylation of glycogen synthase kinase-3β (GSK-3β) and high glucose-caused abolition of cardioprotection induced by sevoflurane postconditioning.Methods:H9c2 cells were incubated in normal glucose (5.56 mmol/L) DMEM culture medium or high glucose (33 mmol/L) DMEM culture medium.The cells were divided into 8 groups ( n=24 each) using a random number table method: normal control group (group NC), normal glucose-cultured hypoxia/reoxygenation (H/R) group (group NH/R), normal glucose-cultured sevoflurane postconditioning group (group NS), normal glucose-cultured GSK-3β inhibitor SB216763 group (group NSB), high glucose-cultured group (group HC), high glucose-cultured H/R group (group HH/R), high glucose-cultured sevoflurane postconditioning group (group HS) and high glucose-cultured GSK-3β inhibitor SB216763 group (group HSB). The model of cardiomyocyte H/R was established by subjecting cardiomyocytes to 3 h of hypoxia followed by reoxygenation.Immediately after onset of reoxygenation, cardiomyocytes were exposed to 2.4% sevoflurane for 30 min in Ns and HS groups.Before the beginning of reoxygenation, GSK-3β inhibitor SB216763 was added to the culture medium with the final concentration of 10 μmol/L in NSB and HSB groups.At 3 h of reoxygenation, the apoptosis rate was determined by Anexin V-PI flow cytometry, the expression of GSK-3β and phosphorylated GSK-3β (p-GSK-3β) was detected by Western blot, superoxide dismutase (SOD) activity was measured using xanthineoxidase method, and lactic dehydrogenase (LDH) activity and malondialdehyde (MDA) content were determined by colorimetric assay. Results:Compared with group NC, apoptosis rate, LDH activity and MDA content were significantly increased, and SOD activity was decreased in group NH/R and group HC, expression of GSK-3β was up-regulated, and expression of p-GSK-3β was down-regulated in group NH/R, expression of p-GSK-3β was up-regulated in group NS, and expression of p-GSK-3β was down-regulated in group HC ( P<0.05). Compared with group NH/R, apoptosis rate, LDH activity and MDA content were significantly decreased, and SOD activity was increased in group NS and NSB groups, and expression of GSK-3β was down-regulated, and expression of p-GSK-3β was up-regulated in group NS ( P<0.05). Compared with group HC, apoptosis rate, LDH activity and MDA content were significantly increased, SOD activity was decreased, expression of GSK-3β was up-regulated, and expression of p-GSK-3β was down-regulated in group HH/R ( P<0.05). Compared with group HH/R, apoptosis rate, LDH activity and MDA content were significantly decreased, and SOD activity was increased in group HSB ( P<0.05). Conclusion:The mechanism by which high glucose abolishes cardioprotection induced by sevoflurane postconditioning is related to inhibiting phosphorylation of GSK-3β.