ENDOTHELIUM-DEPENDENT VASORELAXING ACTIVITY OF AQUEOUS EXTRACTS OF ILEX PARAGUARIENSIS ON MESENTERIC ARTERIAL BED OF RATS

The effects of aqueous extracts of Ilex paraguariensis leaves (AEIp) w ere studied. Mesenteric arterial bed (MAB), precontracted by methoxami ne with or without intact endothelium, was mounted on a tissue bath an d exposed to plant extracts (bolus). The bolus injections of AEIp (300 -1050 mu g) significantly inhibited, in a concentration-dependent mann er, the maximal contractile response induced by methoxamine (30 mu m) in MAB. The endothelium-dependent relaxations were reversed by N-G-nit ro-L-arginine methyl ester (10 mM), whereas methylene blue (100 mu M) was not capable of effectively inhibiting the AEIp-induced vasodilatat ion of MAB. The vasorelaxing effect of AEIp, persisted in the presence of indomethacin (10 mu M). These results suggest the involvement of N O of endothelial source (Or others factors) in this vasodilatory effec t. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.