title: Vasorelaxing Activity of Ulmus davidiana Ethanol Extracts in Rats: Activation of Endothelial Nitric Oxide Synthase.
abstract: Ulmus davidiana var. japonica Rehder (Urticales: Ulmaceae) (UD) is a tree widespread in northeast Asia. It is traditionally used for anticancer and anti-inflammatory therapy. The present study investigated the effect of an ethanol extract of UD on vascular tension and its underlying mechanism in rats. The dried root bark of UD was ground and extracted with 80% ethanol. The prepared UD extract was used in further analysis. The effect of UD on the cell viability, vasoreactivity and hemodynamics were investigated using propidium iodide staining in cultured cells, isometric tension recording and blood pressure analysis, respectively. Low dose of UD (10~100µg/ml) did not affect endothelial cell viability, but high dose of UD reduced cell viability. UD induced vasorelaxation in the range of 0.1~10µg/ml with an ED(50) value of 2µg/ml. UD-induced vasorelaxation was completely abolished by removal of the endothelium or by pre-treatment with L-NAME, an inhibitor of nitric oxide synthase. UD inhibited calcium influx induced by phenylephrine and high K(+) and also completely abolished the effect of L-NAME. Intravenous injection of UD extracts (10~100 mg/kg) decreased arterial and ventricular pressure in a dose-dependent manner. Moreover, UD extracts reduced the ventricular contractility (+dP/dt) in anesthetized rats. However, UD-induced hypotensive actions were minimized in L-NAME-treated rats. Taken together, out results showed that UD induced vasorelaxation and has antihypertensive properties, which may be due the activation of nitric oxide synthase in endothelium.
authors.affiliation: Infection Signaling Network Research Center, Research Institute for Medical Sciences, Department of Physiology, School of Medicine, Chungnam National University, Daejeon 301-131, Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Cho
authors.forename: Myoung Soo
authors.initials: MS
authors.lastname: Park
authors.forename: Sahng Seop
authors.initials: SS
authors.lastname: Kim
authors.forename: Gun
authors.initials: G
authors.lastname: Kang
authors.forename: Sunga
authors.initials: S
authors.lastname: Choi
authors.forename: Yoo Rhan
authors.initials: YR
authors.lastname: Lee
authors.forename: Seok Jong
authors.initials: SJ
authors.lastname: Chang
authors.forename: Kwon Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Sang Do
authors.initials: SD
authors.lastname: Lee
authors.forename: Jin Bong
authors.initials: JB
authors.lastname: Park
authors.forename: Byeong Hwa
authors.initials: BH
authors.lastname: Jeon