Vasodilation by banhabackchulchunmatang, a Chinese medicine, is associated with negative modulation of PKCalpha activation and NO production

Banhabackchulchunmatang (BCT) is a widely used herbal medicine with vasodilatory actions. In the present study, we investigated the subcellular mechanisms of its vascular actions. Both in the presence and absence of endothelium, BCT relaxed vascular strips precontracted with phenylephrine, but the magnitude of relaxation was greater in the presence of endothelium. The relaxation was inhibited by either L-NAME, an NOS inhibitor, or methylene blue, a cGMP inhibitor, indicating the involvement of nitric oxide (NO). The involvement of NO was supported by the increased formation of nitrite from human umbilical vein endothelial cells in the presence of BCT. In vascular strips, BCT lowered the phosphorylation level of the 20 kDa myosin light chains. BCT also directly inhibited phenylephrine-induced protein kinase Calpha (PKCalpha) translocation in freshly isolated single ferret portal vein smooth muscle cells. Together, these effects are likely to contribute to the vasodilatory actions of BCT.