Tetrahydroxystilbene glucoside-induced relaxation of the superior mesenteric artery via both endothelium-dependent and endothelium-independent mechanisms.

Tetrahydroxystilbene glucoside (TSG) is the main water-soluble component in Polygonum multiflorum Thunb, and it has many cardioprotective effects. Although TSG is able to relax blood vessels, its relaxation of rat superior mesenteric arteries and the underlying mechanism of this process are not clearly understood. The aim of the present study was to use in vivo and in vitro models to investigate the arterial relaxation effect of TSG on rat superior mesenteric arteries and the mechanisms involved. We found that TSG concentration-dependently relaxed the superior mesenteric artery with or without endothelium. The vasorelaxation induced by TSG is not related to the vasodilator derived factor NO but is rather by the inhibition of COX-2 activity and decreased TXA2. We also found that the vasorelaxation induced by TSG was attenuated by 4‑AP. Moreover, TSG also inhibited the contraction induced by an increase in external calcium concentration in Ca2+-free medium plus KCl (60 mM). These results suggest that TSG induces relaxation in mesenteric arterial rings through an endothelium-dependent pathway that involves the inhibition of COX-2 activity and decreased in TXA2 and through an endothelium-independent pathway via opening of a voltage-dependent K+ channel, blockade of Ca2+ influx and release of intracellular Ca2+.