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https://repositorio.ufba.br/handle/ri/12166
metadata.dc.type: | Artigo de Periódico |
Title: | Warifteine, a bisbenzylisoquinoline alkaloid, induces relaxation by activating potassium channels in vascular myocytes |
Other Titles: | Clinical and Experimental Pharmacology and Physiology |
Authors: | Assis, Ápio Cláudio de Lima Gonçalves, Islania Giselia Albuquerque Lima, Renata P. C. Almeida, Mônica M. Marinho, Alexsandro Fernandes Barbosa Filho, José Maria Cruz, Jader dos Santos Vasconcelos, Darizy Flavia Silva Amorim de Medeiros, Isac Almeida de |
metadata.dc.creator: | Assis, Ápio Cláudio de Lima Gonçalves, Islania Giselia Albuquerque Lima, Renata P. C. Almeida, Mônica M. Marinho, Alexsandro Fernandes Barbosa Filho, José Maria Cruz, Jader dos Santos Vasconcelos, Darizy Flavia Silva Amorim de Medeiros, Isac Almeida de |
Abstract: | The present study used functional and electrophysiological approaches to investigate the mechanisms by which warifteine, a bisbenzylisoquinoline alkaloid isolated from Cissampelos sympodialis Eichl., causes vasorelaxation of the rat thoracic aorta. 2. Warifteine (1 pmol/L–10 lmol/L) induced concentration- dependent relaxation (pD2 = 9.40 ± 0.06; n = 5) of endothelium-intact aortic rings precontracted with noradrenaline (10–100 lmol/L). The relaxation effects were not attenuated by removal of the endothelium. Warifteine also induced the relaxation of prostaglandin F2a (1–10 mmol/L)-precontracted rings (pD2 = 9.2 ± 0.2; n = 8). In contrast, the relaxant activity of warifteine was nearly abolished in high K+ (80 mmol/L)-precontracted aortic rings. In preparations incubated with 20 mmol/L KCl or with the K+ channel blockers tetraethylammonium (1, 3 and 5 mmol/L), iberiotoxin (20 nmol/L), 4-aminopyridine (1 mmol/L) or glibenclamide (10 lmol/L), the vasorelaxant activity of warifteine was markedly reduced. However, BaCl2 (1 mmol/L) had no effect on the relaxant effects of warifteine. 3. In vascular myocytes, warifteine (100 nmol/L) significantly increased whole-cell K+ currents (at 70 mV). Under nominally Ca2+-free conditions, warifteine did not reduce extracellular Ca2+-induced contractions in rings precontracted with high K+ or noradrenaline (100 lmol/L). 4. Together, the results of the present study indicate that warifteine induces potent concentration-dependent relaxation in the rat aorta via an endothelium-independent mechanism that involves the activation of K+ channels. |
Keywords: | bisbenzylisoquinoline alkaloid potassium channels rat aorta vascular smooth muscle cells vasodilatation warifteine |
Publisher: | Clinical and Experimental Pharmacology and Physiology |
URI: | http://www.repositorio.ufba.br/ri/handle/ri/12166 |
Issue Date: | 2013 |
Appears in Collections: | Artigo Publicado em Periódico (Biologia) |
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