【Abstract】Objective To investigate the effect of PI3K/Akt pathway on the regulation of large conductance Ca2+-activated K+ channel(BK channel) in diabetic coronary smooth muscle cells. Methods Human coronary artery smooth muscle cells(HCASMC) were incubated with different concentrations of glucose(5mM and 15mM).In all cases, controls were performed with cells treated with the corresponding vehicle alone with a final concentration of dimethylsulfoxide (DMSO) at 0.1% (w/w).For DNA-PKcs inhibitor treatment, cells were preincubated with wortmannin (100nM) for 30 min in serum-free medium before treatment with glucose.For reactive oxygen species (ROS) inhibitor treatment, cells were incubated with GKT137831 (20μM) and high concentration of glucose(15mM) for 48h. Expression of DNA-Pkcs、Akt、p-Akt (S473)、 BK-αsubunit and BK-β1 subunits were determined by Western blot.ROS generation in HCASMC was measured in terms of fluorescence using the cell-permeable fluorogenic probe DCFH-DA. Streptozotocin-induced diabetic rats were established successfully by intraperitoneal injection．GKT137831 were fed to diabetic rats and the expression of ROS、DNA-Pkcs、Akt、p-Akt (s473) and BK-α and BK-β1 subunits in rats coronary artery smooth muscle cells were determined.ROS in diabetic rats was measured with cell-permeable fluorogenic probe DCFH-DA. Results Compared with that of HCASMC incubated in 5mM glucose concentration, the expression of DNA-Pkcs、Akt、p-Akt (S473) increased significantly and BK-β1 subunit decreased significantly ( p<0.05), there was no significant change in BK-α subunit expression (p>0.05) of the HCASMC with 15 mM glucose concentration. Compared with the control group,the expression of p-Akt (s473) decreased significantly(p<0.05) and BK-β1 increased significantly (p<0.05) after pretreated with Wortmannin for 30 minutes. The expression of ROS、DNA-Pkcs、Akt、p-Akt (S473) decreased (p<0.05),BK-β1 expression increased significantly after HCASMC incubated with 15mM glucose and GKT137831 for 48h. Compared with normal rats, expression of DNA-Pkcs、Akt、p-Akt(S473)of the diabetic coronary arteries increased by 50%、30% and 30% respectively, and that of BK-β1 subunit decreased by 45%. The expression of ROS、DNA-Pkcs、Akt、p-Akt(S473) decreased （p<0.05) and that of BK-β1 subunit recovered to normal level after the diabetic rats were fed with GKT137831 for 2 weeks. Conclusion PI3K/Akt channel is involved in the regulation of BK channel expression in diabetic coronary smooth muscle cells, and ROS inhibitor GKT137831 can inhibit the generation of ROS and protect coronary smooth muscle cells from injury.