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The Vasorelaxant Effects of Anaxagorea luzonensis A. Grey in the Rat Aorta

Keywords: Ca2+ influx , K+ channels , nitric oxide , endothelium , Anaxagorea luzonensis , vasorelaxation

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The aim of the present research was to study vasorelaxant effects of dichloromethane extract of Anaxagorea luzonensis (CH2Cl2-AL) and its underlying mechanisms. CH2Cl2-AL (1-300 μg mL-1) induced concentration-dependent vasorelaxations which were reduced by endothelial denudation, 300 μM NG-nitro-L-arginine methyl ester (L-NAME) and a combination of 10 μM indomethacin and 300 μM L-NAME, but not indomethacin alone. Raising the extracellular KCl concentration to 60 mM inhibited vasorelaxant responses to CH2Cl2-AL in both endothelium-intact and -denuded rings. Moreover, the responses to CH2Cl2-AL were inhibited by 30 μM barium chloride, 2 μM clotrimazole, 10 μM glibenclamide and 10 μM 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34), but not 1 mM 4-aminopyridine. Pre-incubation with CH2Cl2-AL (1-100 μg mL-1) inhibited contractions induced by CaCl2 in a Ca2+-free, high KCl buffer. The present findings demonstrate, in the rat isolated aorta, that vasorelaxant responses to CH2Cl2-AL are, in part, mediated via the endothelium and NO-dependent pathways. Moreover, activation of KIR, KCa, KATP channels seems to play a role in CH2Cl2-AL-induced responses. Interestingly, Inhibition of extracellular Ca2+ influx is largely involved in the action of CH2Cl2-AL. The present study provides scientific evidence to support the use of CH2Cl2-AL as a vasodilator agent.


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