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

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  μ M) precontracted rings, VPR (0.01-300  μ g/mL) induced a concentration-dependent relaxation (maximum response (MR) = 75.4 ± 4.0%, EC50 = 5.97 (3.8-9.3) μ g/mL, n = 6]); this effect was significantly modified after removal of the endothelium (EC50 = 39.6 (27.2-57.6) μ g/mL, P < 0.05). However, VPF-induced vasorelaxation was less effective compared to VPR. When rings were preincubated with L-NAME (100  μ M) or indomethacin (10  μ M), the endothelium-dependent relaxation induced by VPR was significantly attenuated (MR = 20.9 ± 2.3%, 34.2 ± 2.9%, resp., P < 0.001). 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, n = 5; 50.5 ± 6.0%; 49.3 ± 6.4%; 46.8 ± 6.2%; resp., P < 0.01). In contrast, neither glibenclamide (10  μ M), barium chloride (30  μ M), 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.

DOI: 10.1155/2013/147670

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@inproceedings{Reis2013InvolvementOP, title={Involvement of Potassium Channels in Vasorelaxant Effect Induced by Valeriana prionophylla Standl. in Rat Mesenteric Artery}, author={Milena Ramos Reis and Abrah{\~a}o Alves de Oliveira Filho and Lilia Simone Urzedo Rodrigues and Ja{\'i}se Paiva Ara{\'u}jo and Priscilla Maria Pereira Maciel and Jamile Morais de Albuquerque and Valdir Cehinel Filho and A. C{\'a}ceres and Josmara Bartolomei Fregoneze and Isac Almeida de Medeiros and Dar{\'i}zy Fl{\'a}via Silva}, booktitle={Evidence-based complementary and alternative medicine : eCAM}, year={2013} }