Impairment of Endothelial Cell Function Induced by Hemoglobin A1c and the Potential Mechanisms

Objective: Hemoglobin A 1c (HbA 1c ) concentrations reflect glycemic control and diabetic complications. However, there is little evidence supporting the pathological role of HbA 1c in the development and progression of diabetic complications. We investigated the impact of HbA 1c on endothelial cell function and the potential mechanisms. Methods: The effects of HbA 1c on the viability and migration of human umbilical vein endothelial cells (HUVECs) were measured by the Cell Counting Kit-8 and a wound healing scratch assay, respectively. Production of nitric oxide (NO) and reactive oxygen species was measured by the nitrate reductase colorimetric method and flow cytometry, respectively. The expression of endothelial nitric oxide synthase (eNOS) mRNA was quantitated by reverse-transcriptase PCR. The expression of eNOS, p-AMPK, and NOX4 proteins was detected by Western blot. Results: High concentrations of HbA 1c reduced the viability and migration of HUVECs in a dose- and time-dependent manner. High concentrations of HbA 1c inhibited production of NO but increased production of ROS. Incubation with increasing concentrations of HbA 1c downregulated the expression of eNOS mRNA, decreased expression of eNOS and p-AMPK, and upregulated expression of NOX4. Conclusion: These findings provide direct evidence that HbA 1c is involved in the development and progression of the cardiovascular complications of diabetes.