title: Vascular responses to extractable fractions of Ilex paraguariensis in rats fed standard and high-cholesterol diets.
abstract: The authors investigated the vasorelaxant properties of the aqueous (Aq-EF) and acid n-butanolic (acn-BuOH) extractable fractions from Ilex paraguariensis leaves. Perfusion pressure was evaluated using isolated and perfused mesenteric arterial beds (MABs) from rats fed hypercholesterolemic and standard diets. Extract-induced vasorelaxation in the presence and absence of various inhibitors was examined following precontraction of the MABs with methoxamine (30 microM) solution. In hypercholesterolemic-diet rats, relaxation in intact MABs was significantly decreased with ac-n-BuOH-EF bolus (300, 600, 900 microg) in comparison to those in standard-diet rats. After the endothelium was stripped from the MABs, the vascular responses to ac-n-BuOH-EF and 900 microg bolus of Aq-EF were significantly changed. Treatment of the MABs with an inhibitor of nitric oxide synthase, N(G)-nitro-L-arginine methylester hydrochloride (L-NAME, 10 mM), did not change either ac-n-BuOH-EF- or Aq-EF-induced vasodilation except for the 900 microg bolus of Aq-EF. The guanilate cyclase inhibitor methylene blue (100 microM) did not affect vasodilation for either fraction in the MABs from the hypercholesterolemic-diet rats. The chronic oral administration of I. paraguariensis extract in hypercholesterolemic-diet rats resulted in a significant reduction in serum levels of cholesterol and triglycerides. These results suggest that I. paraguariensis ac-n-BuOH-EF and Aq-EF induce vasodilation in standard-diet rats in a dose-dependent manner and that the hypercholesterolemic diet substantially reduced the effect of ac-n-BuOH-EF on precontracted MABs.
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas-Fisiologia Animal Comparada, Fundação Universidade Federal do Rio Grande, Brazil.
authors.forename: Fabiana L
authors.initials: FL
authors.lastname: Paganini Stein
authors.forename: Bruno
authors.initials: B
authors.lastname: Schmidt
authors.forename: Eliana Badiale
authors.initials: EB
authors.lastname: Furlong
authors.forename: Leonor A
authors.initials: LA
authors.lastname: Souza-Soares
authors.forename: Maria Cristina Flores
authors.initials: MC
authors.lastname: Soares
authors.forename: Marta R Cezar
authors.initials: MR
authors.lastname: Vaz
authors.forename: Ana L
authors.initials: AL
authors.lastname: Muccillo Baisch
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D006937:Hypercholesterolemia / Q000517:prevention & control*; D030019:Ilex paraguariensis; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010936:Plant Extracts