title: 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.
authors.affiliation: Laboratório 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.
authors.forename: Milena Ramos
authors.initials: MR
authors.lastname: Reis
authors.forename: Abrahão Alves
authors.initials: AA
authors.lastname: de Oliveira Filho
authors.forename: Lilia Simone Urzedo
authors.initials: LS
authors.lastname: Rodrigues
authors.forename: Jaíse Paiva
authors.initials: JP
authors.lastname: Araújo
authors.forename: Priscilla Maria Pereira
authors.initials: PM
authors.lastname: Maciel
authors.forename: Jamile Morais
authors.initials: JM
authors.lastname: de Albuquerque
authors.forename: Valdir
authors.initials: V
authors.lastname: Cehinel Filho
authors.forename: Armando
authors.initials: A
authors.lastname: Cáceres
authors.forename: Josmara Bartolomei
authors.initials: JB
authors.lastname: Fregoneze
authors.forename: Isac Almeida
authors.initials: IA
authors.lastname: de Medeiros
authors.forename: Darizy Flávia
authors.initials: DF
authors.lastname: Silva
references.citation: Prog Biophys Mol Biol. 2010 Sep;103(1):95-101
references.pmid: 19835907
references.citation: Evid Based Complement Alternat Med. 2011;2011:312320
references.pmid: 21754942
references.citation: Am J Physiol Heart Circ Physiol. 2003 Jun;284(6):H2325-34
references.pmid: 12598232
references.citation: Kidney Int. 2000 Mar;57(3):838-45
references.pmid: 10720937
references.citation: J Pharm Pharmacol. 1994 Apr;46(4):242-51
references.pmid: 8051606
references.citation: Am J Physiol Cell Physiol. 2004 Jul;287(1):C125-34
references.pmid: 14985237
references.citation: J Smooth Muscle Res. 2008 Apr;44(2):65-81
references.pmid: 18552454
references.citation: Br J Pharmacol. 1999 Dec;128(7):1602-8
references.pmid: 10602342
references.citation: Basic Clin Pharmacol Toxicol. 2011 Dec;109(6):465-75
references.pmid: 21726408
references.citation: Pharmacol Biochem Behav. 2003 Jun;75(3):501-12
references.pmid: 12895668
references.citation: Am J Physiol. 1991 Mar;260(3 Pt 2):H927-34
references.pmid: 1900393
references.citation: Pharm Weekbl Sci. 1985 Aug 23;7(4):167-8
references.pmid: 4047916
references.citation: Biochem Biophys Res Commun. 1985 Jun 28;129(3):877-84
references.pmid: 3925951
references.citation: Ann Med. 2012 Nov;44(7):694-716
references.pmid: 21895549
references.citation: Physiology (Bethesda). 2006 Feb;21:69-78
references.pmid: 16443824
references.citation: Acta Physiol Scand. 1998 Dec;164(4):549-57
references.pmid: 9887977
references.citation: Heart Vessels. 2010 Nov;25(6):556-64
references.pmid: 20936291
references.citation: Exp Biol Med (Maywood). 2010 Jan;235(1):10-22
references.pmid: 20404014
references.citation: Br J Pharmacol. 1998 Jan;123(1):106-12
references.pmid: 9484860
references.citation: Phytomedicine. 1997 Jun;4(2):151-66
references.pmid: 23195404
references.citation: Br J Pharmacol. 1969 Jul;36(3):549-60
references.pmid: 4389283
references.citation: Nature. 1980 Nov 27;288(5789):373-6
references.pmid: 6253831
references.citation: Am J Physiol. 1970 Dec;219(6):1698-705
references.pmid: 4320911
references.citation: Am J Physiol Lung Cell Mol Physiol. 2004 May;286(5):L909-17
references.pmid: 14617522
references.citation: Pflugers Arch. 2006 Oct;453(1):33-41
references.pmid: 16847697
references.citation: Am J Physiol. 1995 Apr;268(4 Pt 1):C799-822
references.pmid: 7733230
references.citation: J Nat Prod. 2004 Jul;67(7):1135-40
references.pmid: 15270567
references.citation: Cell Calcium. 2001 May;29(5):327-34
references.pmid: 11292389
references.citation: Am J Physiol Renal Physiol. 2001 May;280(5):F739-47
references.pmid: 11292615