Mechanistic study of endothelium independent vasodilation effects of wogonin

Abstract

Scutellaria baicalensis Georgi, locally known as HuangQin, and commonly as Baikal or Chinese skullcap, is an important herb in Chinese traditional medicine. The flavonoids from this plant are main active substances responsible for its medicinal applications. Wogonin is one such active ingredient derived from this plant. Here, we investigated the mechanism of the vasodilation effect of wogonin on isolated rat thoracic aortas. For this study, endothelium intact and endothelium removed thoracic aortic rings were prepared from rats. Using a tension transducer, the tension of the rat thoracic aortic rings was recorded. Results showed that wogonin is able to relax the endothelium-intact aortic rings, but L-NAME, indomethacin (Indo), and methylene blue (MB) could not reduce the tension in these rings. Wogonin was also able to relax endotheliumremoved rings. However, treatment with tetraethylammonium (TEA), BaCl2, glibenclamide (Gly), 4-aminopyridine (4-AP), and verapamil (Ver) had no effect on vasodilation induced by wogonin. Using wogonin to pre-treat endothelium-removed aortic rings reduced the contraction induced by K+. Pre-treatment of endothelium-removed aortic rings with wogonin markedly reduced the contraction induced by 10-6 M PE in Ca2+-free solution. It could be concluded that L-type calcium channels and intracellular Ca2+ release is inhibited by wogonin.