The mechanism of vasorelaxation induced by Schisandra chinensis extract in rat thoracic aorta

• Published in: Journal of ethnopharmacology 2009-01, Vol.121 (1), p.69-73
• Main Authors: Park, Ji Young, Shin, Hwa Kyoung, Lee, You Jin, Choi, Young Whan, Bae, Sun Sik, Kim, Chi Dae
• Format: Article
• Language: English
• Subjects: Animals; aorta; Aorta, Thoracic - drug effects; Aorta, Thoracic - physiology; Biological and medical sciences; chloroform; dephosphorylation; dose response; Dose-Response Relationship, Drug; Endothelium; Endothelium, Vascular - drug effects; Endothelium, Vascular - physiology; enzyme inhibitors; Fruit - chemistry; General pharmacology; hexane; Hexane extract; In Vitro Techniques; indomethacin; Male; Medical sciences; medicinal plants; medicinal properties; methanol; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - physiology; Myosin light chain; myosin light chains; Myosin-Light-Chain Kinase - antagonists & inhibitors; Myosin-Light-Chain Kinase - metabolism; Myosin-Light-Chain Phosphatase - antagonists & inhibitors; Myosin-Light-Chain Phosphatase - metabolism; Nitric oxide; Nitric Oxide - physiology; nitric oxide synthase; Oriental traditional medicine; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; phenylephrine; Phosphorylation; plant extracts; Plant Extracts - chemistry; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Rats; Rats, Sprague-Dawley; Schisandra - chemistry; Schisandra chinensis; signal transduction; Vasodilation; Vasodilation - drug effects; Vasodilation - physiology; vasodilator agents
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2008.09.031

Schisandra chinensis (SC) is a known medical herb for the treatment of cardiovascular symptoms associated with menopausal symptoms in Korea. However, the pharmacological action mechanisms involved have not been well studied. This study was aimed to investigate the vascular effects of SC in rat thoracic aorta. We isolated the hexane, chloroform, and methanol extracts from SC and evaluated their vasodilatory effects in the rat thoracic aorta. Hexane extracts of SC (SCHE, 5 × 10 −5 to 10 −3 g/L) caused a concentration-dependent relaxation in both endothelium-intact and -denuded aortas. The relaxant effect of SCHE on the endothelium-intact aorta was more prominent than on the endothelium-denuded aorta. The former was significantly attenuated by L-NAME, a nitric oxide synthase inhibitor, and ODQ, a soluble guanyl cyclase inhibitor, but not by tetraethylammonium, a nonselective blocker of K + channels, and indomethacin, a cyclooxygenase inhibitor. Furthermore, SCHE caused nitrite production as well as eNOS activation in aortic segments, suggesting implication of NO signal pathway in SCHE-induced relaxation. In endothelium-denuded aorta, SCHE-induced vasorelaxation was also attenuated by calyculin A, an inhibitor of myosin light chain (MLC) phosphatase, but not by ML-9, a MLC kinase inhibitor, suggestive of implication of MLC phosphatase activation. Phenylephrine-enhanced MLC phosphorylation ratio was significantly attenuated by SCHE, which was recovered to the control level by pretreatment with calyculin A. Taken collectively, these findings suggest that the vascular relaxation evoked by SCHE was mediated by not only endothelium dependent NO pathway but also direct effect on vascular smooth muscle cell via dephosphorylation of MLC.