Mechanisms involved in the vasodilator effect of the flavanol floranol in rat small mesenteric arteries.

The mechanism underlying the vasodilator effect of the flavonoid floranol was studied in rat small mesenteric arteries. Floranol produced a concentration-dependent vasorelaxant effect in endothelium-containing and endothelium-denuded vessels pre-contracted with phenylephrine, which was more potent in endothelium-intact vessels. In endothelium-intact mesenteric arteries, l-NAME but not indomethacin produced a shift to the right in the vasorelaxant effect of floranol. In endothelium-denuded vessels TEA and BaCl2 did not change the floranol-induced vasorelaxation. When endothelium-denuded vessels were pre-contracted with 50 mM KCl, floranol induced a vasorelaxant effect comparable with phenylephrine pre-contracted vessels. We conclude that floranol is a new vasodilator compound in rat small mesenteric arteries. Part of this effect is dependent on endothelial nitric oxide (NO) and part is dependent on the inhibition of voltage-dependent calcium channels in the smooth muscle cells.