Ginsenoside R b3 attenuates oxidative stress and preserves endothelial function in renal arteries from hypertensive rats

Background and Purpose P anax ginseng is commonly used to treat cardiovascular conditions in Oriental countries. This study investigated the mechanisms underlying the vascular benefits of ginsenoside R b3 ( R b3) in hypertension. Experimental Approach Rings of renal arteries were prepared from spontaneously hypertensive rats ( SHR s) and normotensive Wistar‐Kyoto ( WKY ) rats and were cultured ex vivo for 8 h. Contractile responses of the rings were assessed with myograph techniques. Expression of NADPH oxidases was assessed by W estern blotting and immunohistochemistry. Reactive oxygen species ( ROS ) were measured using dihydroethidium fluorescence imaging and production of NO was determined using the fluorescent NO indicator DAF‐FM diacetate in human umbilical vein endothelial cells. Key Results E x vivo treatment with R b3 concentration‐dependently augmented endothelium‐dependent relaxations, suppressed endothelium‐dependent contractions and reduced ROS production and expressions of NOX ‐2, NOX ‐4 and p67 phox in arterial rings from SHR . Rb3 treatment also normalized angiotensin II ( A ng II )‐stimulated elevation in ROS and expression of NOX ‐2 and NOX ‐4 in arterial rings from WKY rats. R b3 inhibited A ng II ‐induced reduction of NO production and phosphorylation of endothelial NOS in cultures of human umbilical vein endothelial cells. R b3 also inhibited oxidative stress in renal arterial rings from hypertensive patients or in A ng II ‐treated arterial rings from normotensive subjects. Conclusion and Implications Ex vivo   R b3 treatment restored impaired endothelial function in arterial rings from hypertensives by reversing over‐expression of NADPH oxidases and over‐production of ROS , and improved NO bioavailability. Our findings suggest that medicinal plants containing R b3 could decrease oxidative stress and protect endothelial function in hypertension.