Abstract
Epigallocatechin gallate (EGCG) has been shown to have antihypertensive activity. However, the role of epigallocatechin gallate (EGCG) in improving vascular function via modulation of endothelial nitric oxide synthase (eNOS) in hypertensive subjects is not well researched. Angiotensin II-infused hypertensive mice (8-10 weeks old) received EGCG (50 mg/kg/day) for 14 days via oral gavage. The arterial systolic blood pressure (SBP) was measured using the tail-cuff method every three days. At the end of the treatment, the vascular reactivity of the isolated aortae was studied using wire myographs. The level of nitric oxide (NO), cyclic guanosine monophosphate (cGMP) and tetrahydrobiopterine (BH4) were determined using assay kits while the presence of proteins (NOS, p-eNOS and NOx-2) were determined using by Western blotting. In vivo treatment with EGCG for 14 days significantly attenuated the increase in SBP, alleviated the vascular dysfunction, increased the vascular cGMP and BH4 level as well as the expression of p-eNOS and decreased elevated ROS level and NOx-2 protein in angiotensin II-infused hypertensive mice. Collectively, treatment with EGCG in hypertensive mice exerts a blood pressure lowering effect which is partly attributed to the improvement in the vascular function due to its ability to reduce vascular oxidative stress in the aortic tissue leading to a decrease in eNOS uncoupling thus increasing NO bioavailability.