Role of autophagy in reduction of high glucose and hypoxia-reoxygenation injury to isolated cardiomyocytes by dexmedetomidine in rats / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of autophagy in reduction of high glucose and hypoxia-reoxygenation (HG+ H/R) injury to isolated cardiomyocytes by dexmedetomidine in rats.Methods:The normally cultured rat H9c2 cardiomyocytes at the logarithmic growth phase were seeded in 6-well plates at a density of 1×10 6 cells/ml and divided into 4 groups ( n=15 each) using a random number table method: control group (group C), group HG+ H/R, dexmedetomidine group (group DEX) and dexmedetomidine+ autophagy inhibitor 3-methylpurine group (group 3-MA). The cells were incubated in culture medium with 1% fetal bovine serum + 1% double antibody for 24 h when the cell density reached 50%.To establish HG+ H/R injury model, the cardiomyocytes were cultured in high-glucose culture medium (glucose concentration of 33 mmol/L) for 24 h, and then incubated in a 37 ℃ incubator (95% N 2+ 5%CO 2) for 4 h followed by reoxygenation (90%O 2+ 10%CO 2) for 2 h. Dexmedetomidine was added until the final concentration reached 5 μmol/L at 1 h before hypoxia in DEX and 3-MA groups, and 3-MA was added until the final concentration reached 5 μmol/L at 1 h of incubation with dexmedetomidine.At 2 h after reoxygenation, the cell viability was recorded by the cell counting kit-8 assay, lactate dehydrogenase (LDH) activity was detected by LDH kit, the expression of autophagy-related protein LC3, P62 and Beclin-1 was detected by Western Blot, the ratio of LC3Ⅱ/LC3Ⅰwas calculated, and the expression of P62 and Beclin-1 mRNA was detected by real-time polymerase chain reaction. Results:Compared with group C, the cell viability was significantly decreased in HG+ H/R, DEX and 3-MA groups, LDH activity in the supernatant was increased and expression of P62 was decreased in HG+ H/R and 3-MA groups, ratio of LC3Ⅱ/LC3Ⅰwas decreased in group 3-MA, and the expression of Beclin-1 was down-regulated in group HG+ H/R ( P<0.05). Compared with HG+ H/R group, LDH activity in the supernatant was significantly decreased, expression of Beclin-1, P62 and its mRNA was up-regulated, and ratio of LC3Ⅱ/LC3Ⅰwas increased in DEX group, and LDH activity in the supernatant was increased in group 3-MA ( P<0.05). Compared with DEX group, cell viability were decreased, LDH activity in the supernatant was increased, Beclin-1, P62 and its mRNA was down-regulated, and ratio of LC3Ⅱ/ LC3Ⅰwas decreased in group 3-MA ( P<0.05). Conclusion:Autophagy is involved in the reduction of HG+ H/R injury to isolated cardiomyocytes by dexmedetomidine in rats.