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Evidence-Based Complementary and Alternative Medicine
Volume 2013 (2013), Article ID 147670, 10 pages
http://dx.doi.org/10.1155/2013/147670
Research Article

Involvement of Potassium Channels in Vasorelaxant Effect Induced by Valeriana prionophylla Standl. in Rat Mesenteric Artery

1Laboratório de Fisiologia e Farmacologia Endócrina e Cardiovascular, Departamento de Biorregulação, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Avenida Reitor Miguel Calmon, Vale do Canela, 40110-902 Salvador, BA, Brazil
2Laboratório de Farmacologia Cardiovascular, Centro de Biotecnologia, Universidade Federal da Paraíba, Cidade Universitária, 58051-900 João Pessoa, PB, Brazil
3Laboratório de Neurociências, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Avenida Reitor Miguel Calmon, Vale do Canela, 40110-902 Salvador, BA, Brazil
4Núcleo de Investigações Químico-Farmacêuticas, Centro de Ciências da Saúde, Universidade do Vale do Itajaí, Rua Uruguai, 458 Centro, 88302-202 Itajaí, SC, Brazil
5Facultad de Ciencias Químicas y Farmacia, Universidad de San Carlos de Guatemala (USAC), 01012 Ciudad de Guatemala, Guatemala

Received 23 March 2013; Revised 7 July 2013; Accepted 8 July 2013

Academic Editor: Jae Youl Cho

Copyright © 2013 Milena Ramos Reis et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Assays in vitro and in vivo were performed on extract from roots and leaves from the Valeriana prionophylla Standl. (VPR and VPF, resp.). In phenylephrine (1 μM) precontracted rings, VPR (0.01–300 μg/mL) induced a concentration-dependent relaxation (maximum response (MR) = 75.4 ± 4.0%, EC50 = 5.97 (3.8–9.3) μg/mL, ]); this effect was significantly modified after removal of the endothelium (EC50 = 39.6 (27.2–57.6) μg/mL, ). However, VPF-induced vasorelaxation was less effective compared to VPR. When rings were preincubated with L-NAME (100 μM) or indomethacin (10 μM), the endothelium-dependent relaxation induced by VPR was significantly attenuated (MR = 20.9 ± 2.3%, 34.2 ± 2.9%, resp., ). In rings denuded endothelium, precontracted with KCl (80 mM), or in preparations pretreated with KCl (20 mM) or tetraethylammonium (1 or 3 mM), the vasorelaxant activity of VPR was significantly attenuated (MR = 40.0 ± 8.2, ; 50.5 ± 6.0%; 49.3 ± 6.4%; 46.8 ± 6.2%; resp., ). In contrast, neither glibenclamide (10 μM), barium chloride (30 μM), nor 4-aminopyridine (1 mM) affected VPR-induced relaxation. Taken together, these results demonstrate that hypotension induced by VPR seems to involve, at least in part, a vascular component. Furthermore, endothelium-independent relaxation induced by VPR involves K+ channels activation, most likely due to BKCa channels, in the rat superior mesenteric artery.