The Involvement of ATP-Sensitive Potassium Channels in the Nebivolol-Induced Relaxation of Endothelium-Intact Aorta Isolated from Rats

Authors : Hande Ozge ALTUNKAYNAK-CAMCA

Pages : 201-206

Doi:10.19127/mbsjohs.708294

View : 16 | Download : 7

Publication Date : 2020-08-31

Article Type : Research Paper

Abstract :Objective: Nebivolol is a highly selective beta-1 adrenergic receptor blocker with additional vasorelaxant properties. The vasorelaxant effect of nebivolol has been mainly attributed to endothelium-dependent mechanisms including beta-adrenergic receptors. However, the involvement of ATP-sensitive potassium insert ignore into journalissuearticles values(KATP); channels, another potential mechanism for vasorelaxant effect, in the vasorelaxant response to nebivolol remains unclear. Therefore, this study was aimed to investigate the role of KATP channels in the nebivolol-induced vasorelaxation in the isolated rat aorta Methods: The rat thoracic aortic rings isolated from Sprague-Dawley rats were mounted in organ bath chambers containing Krebs-Henseleit solution at 37 oC continuously bubbled with 95% O2 and 5% CO2. After an equilibration period, the presence of endothelium was confirmed by the response insert ignore into journalissuearticles values(more than 50%); to acetylcholine insert ignore into journalissuearticles values(10 μM); in aortic rings precontracted with phenylephrine insert ignore into journalissuearticles values(1 μM);. After washout, in control group, the endothelium-intact aortic rings were contracted by potassium chloride insert ignore into journalissuearticles values(30 mM); before the cumulative addition of nebivolol insert ignore into journalissuearticles values(0.0001-100 μM);. In some experiments, the relaxant response to nebivolol insert ignore into journalissuearticles values(0.0001-100 μM); was also obtained in the presence of glibenclamide insert ignore into journalissuearticles values(KATP channel blocker, 10 μM); or Nω-Nitro-L-arginine methyl ester insert ignore into journalissuearticles values(L-NAME: eNOS inhibitor, 100 μM); in the endothelium-intact aortic rings precontracted with potassium chloride insert ignore into journalissuearticles values(30 mM);. Data were presented as means±SEM. Multiple comparisons of groups were performed by using ANOVA followed by post-hoc Bonferroni test. Results: Nebivolol elicited a concentration dependent vasorelaxant effect in the endothelium-intact aortic rings. Relaxant response to nebivolol was significantly inhibited by the presence of glibenclamide or L-NAME insert ignore into journalissuearticles values(p< 0.05);. Although Emax values were not found significantly different among groups, pD2 values of nebivolol were reduced in the endothelium-intact aortic rings incubated with glibenclamide or L-NAME. Conclusion: These results demonstrate for the first time the involvement of KATP channels in the nebivolol-induced vasorelaxation in the endothelium-intact aorta precontracted with potassium chloride.
Keywords : Nebivolol, vasorelaxation, ATP sensitive potassium channels, nitric oxide, rat aorta