Antihypertensive, vasorelaxant and inotropic effects of an ethanolic extract of the roots of Saururus chinensis

AIM OF THE STUDY: The present study was performed to evaluate the cardiovascular effects of ethanolic extract of the roots of Saururus chinensis (EERSC) in rats. MATERIALS AND METHODS: The effects of EERSC on the vascular responses of isolated rat aorta, the cardiac functions in isolated rat heart, and the antihypertensive effects in spontaneously hypertensive rats (SHRs) were evaluated. RESULTS: In isolated rat aortic preparations, EERSC exhibited a potent vasorelaxant effect with EC(50) value of 9.1 microg/ml. This relaxation was significantly inhibited by denudation of endothelial layer or by pretreatment with N(G)-nitro-l-arginine methyl ester. In addition, the raising extracellular K(+) (45 mM), or pretreatment with tetraethylammonium (10 mM) significantly inhibited EERSC-induced vasorelaxation in endothelium-denuded aortic rings. In isolated rat hearts, EERSC significantly reduced cardiac functions such as left ventricle pressure and heart rate. In an antihypertensive study with SHRs, long-term oral administrations of EERSC decreased blood pressure of SHRs (approximately 20 mmHg). CONCLUSIONS: These results suggest that chronic treatment with EERSC exerts an antihypertensive effect in SHRs, and its direct vasorelaxant properties and negative inotropic actions may contribute to reduce the elevated blood pressure.