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Schisandra chinensis extract in rat thoracic aorta

Date:2016/3/2 7:25:35


Schisandra chinensis extract 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.

Materials and methods

We isolated the hexane, chloroform, and methanol extracts from SC and evaluated their vasodilatory effects in the rat thoracic aorta.

Results

Hexane extracts of SC (Schisandra chinensis extract, 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, Schisandra chinensis extract 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.

Conclusions

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.

Abbreviations

SC, Schisandra chinensis; Schisandra chinensis extract, hexane extract of Schisandra chinensis; MLC, myosin light chain; NO, nitric oxide; l-NAME, NG-nitro-l-arginine methyl ester; ODQ, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one; PE, phenylephrine

Keywords

Schisandra chinensis; Hexane extract; Vasodilation; Endothelium; Nitric oxide; Myosin light chain