Salvianolic acid B possesses vasodilation potential through NO and its related signals in rabbit thoracic aortic rings

Salviae miltiorrhizae, a traditional Chinese medicine, is widely used in the treatment of cardiovascular and cerebrovascular diseases. Salvianolic acid B is identified as one of the most important water-soluble active ingredients in Salviae miltiorrhizae and associated with the activation of Ca2+ channel of cytomembrane. But the further mechanism of action was not very clearly. In our study, we investigated the vasodilation activity of salvianolic acid B using the isolated thoracic aortic rings from Japanese white rabbit. Salvianolic acid B significantly released the contraction of the isolated thoracic aortic rings induced by phenylephrine and CaCl2 while had no effects on the aortic rings with KCl stimulated. Different with Di-ao-xin-xue-kang capsule, salvianolic acid B caused an increase of Ca2+ in cytoplasm from not only activation of Ca2+ channel in cytomembrane but also release of endogenous Ca2+. Then, a series of endogenous Ca2+ inhibitors were pretreated to explore the mechanism of salvianolic acid B, and the results provided further evidences that salvianolic acid B causes intracellular calcium release in ryanodine receptors-dependent manners. Moreover, combining l-arginine (l-Arg) with salvianolic acid B promoted the vasodilation activity suggesting a relationship with nitric oxide (NO). To further investigated its mechanism, both guanylate cyclase (GC) inhibitor and NO Synthase inhibitor were used and demonstrated to block vasodilation activity of the aortic rings. Our findings reveal a NO-sGC-cGMP signals dependence mechanism of salvianolic acid B on its vasodilation activity which provide an evidence for its subsequent application in clinic.