Abstract: Objective:To investigate the inhibitory effect of coenzyme Q10 (Co-Q10) on the apoptosis of human coronary endothelial cells (HCAECs) induced by highglucose, and to elucidate its possible mechanism. Methods:The HCAECs were divided into control group, high glucose group and high glucose combined with 5, 10,and20 μmol·L^-1 Co-Q10 treatment groups;the HCAECs in control group were cultured for 24 h using a routine culture method. The cells in high glucose group were treated with 30 mmol·L^-1 glucose for 24 h;the cells in high glucose combined with 5, 10,and 20 μmol·L^-1 Co-Q10 treatment groups were treated with 5, 10,and 20 μmol·L^-1 Co-Q10 combined with 30 mmol·L^-1 glucose for 24 h, respectively. The cell viabilities of HCAECs in various groups were measured by CCK-8 assay. The apoptotic rates of HCAECs in high glucose group and high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group were detected by Hoechst-PI double staining. The cell mitochondrial membrane potentials of HCAECs in high glucose group and high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group were determined by Mito-tracker staining.The mitochondrial reative oxygen species (mtROS) levels in the HCAECs in high glucose group and high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group were measured by MitoSox staining. The protein expression levels of B cell lymphoma/leukemia 2 protein (Bcl-2), Bcl-2 assaciated X protein (Bax), Bcl-2 assaciated death promoter (Bad) and X-linked inhibitor of apoptosis protein (x-IAP) in the HCAECs in high glucose group and high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group were detected by Western blotting method. Results:Compared with control group, the cell viability of HCAECs in high glucose group was significantly reduced (P<0.01); compared with high glucose group, the cell viabilities of HCAECs in high glucose combined with 5, 10,and 20 μmol·L^-1 Co-Q10 treatment groups were significantly increased(P<0.05 or P<0.01), especially in high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group (P<0.01). Compared with high glucose group, the apoptotic rate, the mitochondrial membrane potential and the mtROS level of HCAECs in high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group were significantly decreased (P<0.01).The Western blotting results showed that compared with high glucose group, the expression levels of Bax and Bad proteins in the HCAECs in high glucose combined with 10 μmol·L^-1 Co-Q10 treatment group were decreased significantly(P<0.01), and the expression levels of Bcl-2 and x-IAP proteins were increased significantly (P<0.01). Conclusion:Co-Q10 may reduce the apoptosis of HCAECs induced by high glucose through inhibiting the mitochondrial apoptosis-related pathway to ptotect the cells.

Key words: coenzyme Q10, high glucose, human coronary endothelial cells, apoptosis, mitochondrial stress