[Vasodilation effect and mechanism of extraction of Tongmai Yangxin Pills (TMYX) on isolated rat mesenteric artery].

The aim of the present study is to evaluate the vasodilation effects of Tongmai Yangxin Pills (TMYX) on rat mesenteric artery as well as its mechanism of action. The relaxation effects of TMYX extracts with different concentrations were determined on isolated rat mesenteric artery in normal condition as well as pretreating by phenylephrine and KCl. Vascular relaxation effects of TMTX were also determined in mesenteric artery preincubated with L-ANME and indomethacin or in endothelium denuded mesenteric artery. Moreover, effects of TMYX by 50 mg·L⁻¹ on NO secretion and the phosphorylation of eNOS in a cellular model of human umbilical vein endothelial cell (HUVEC) pretreated with or without L-NAME were also observed. The experimental results showed that TMYX has no obvious effect on vasodilation of arteries in normal or KCl pretreated condition, while it can dose-dependently relax the rat mesenteric artery with intact endothelium stimulated with phenylephrine at a maximal diastolic rate of (64.71±10.03)%. After preincubating with L-NAME for 15 min or removal of mesenteric artery endothelium, the maximal diastolic rate was decreased to (35.77±8.93)% and (25.85±10.84)% respectively. However, preincubating with indomethacin had no inhibitory effect on TMYX induced vascular relaxation. Meanwhile, TMYX at 50 mg·L⁻¹ could increase the expression of P-eNOS and the secretion of NO in HUVEC. L-NAME significantly inhibited NO release and phosphorylation of eNOS induced by TMYX. The results suggested TMYX exerted endothelium-dependent relaxation effects against PE-induced contractions of isolated rat mesenteric artery through NO-cGMP signaling pathway.