The objective of the study was to investigate the mechanism of the relaxant activity of the ent-15α-acetoxykaur-16-en-19-oic acid (KA-acetoxy). In rat mesenteric artery rings, KA-acetoxy induced a concentration-dependent relaxation in vessels precontracted with phenylephrine. In the absence of endothelium, the vasorelaxation was significantly shifted to the right without reduction of the maximum effect. Endothelium-dependent relaxation was significantly attenuated by pretreatment with L-NAME, an inhibitor of the NO-synthase (NOS), indomethacin, an inhibitor of the cyclooxygenase, L-NAME + indomethacin, atropine, a nonselective antagonist of the muscarinic receptors, ODQ, selective inhibitor of the guanylyl cyclase enzyme, or hydroxocobalamin, a nitric oxide scavenger. The relaxation was completely reversed in the presence of L-NAME + 1 mM L-arginine or L-arginine, an NO precursor. Diterpene-induced relaxation was not affected by TEA, a nonselective inhibitor of K+ channels. The KA-acetoxy antagonized CaClinduced contractions in a concentration-dependent manner and also inhibited an 80 mM KCl-induced contraction. The KA-acetoxy did not interfere with Ca 2+ release from intracellular stores. The vasorelaxant induced by KA-acetoxy seems to involve the inhibition of the Ca 2+ influx and also, at least in part, by endothelial muscarinic receptors activation, NO and PGIrelease. © 2012 Êurica Adélia Nogueira Ribeiro et al.
Ribeiro, E. A. N., Herculano, E. D. A., Costa, C. D. F. D., Furtado, F. F., Da-Cunha, E. V. L., Barbosa-Filho, J. M., … Medeiros, I. A. D. (2012). The ent -15 α -acetoxykaur-16-en-19-oic acid relaxes rat artery mesenteric superior via endothelium-dependent and endothelium-independent mechanisms. Evidence-Based Complementary and Alternative Medicine, 2012. https://doi.org/10.1155/2012/472821