34-40Scutellaria 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