Effects of putative K+ channel blockers on beta-adrenoceptor-mediated vasorelaxation of rat mesenteric artery
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AbstractThe aim of our study was to investigate the contribution of Ca2+-activated K+ channels (K-Ca channels) and ATP-sensitive K+ channels (K-ATP channels) to the vasodilator responses to beta-adrenoceptor agonists in the rat isolated mesenteric artery. Isoprenaline and fenoterol concentration-dependently relaxed the phenylephrine-precontracted endothelium-intact arterial rings with 50% inhibitory concentration (IC50) of 0.0314 +/- 0.027 mu M (n = 20) and 0.40 +/- 0.04 mu M (n = 11), respectively. Charybdotoxin (100 nM) displaced the isoprenaline or fenoterol logarithmic concentration-relaxation curve to the right in the absence and presence of endothelium. In contrast, glibenclamide (10 mu M) did not affect the effects of isoprenaline and fenoterol, whereas glibenclamide (3 mu M) significantly inhibited the cromakalim-induced vasorelaxation. Neither charybdotoxin (100 nM) nor glibenclamide (10 mu M) influenced the vasorelaxation induced by forskolin. Ba2+, a nonselective blocker of K+ channels, inhibited the relaxant effects of isoprenaline and forskolin. These results suggest that K-Ca but not K-ATP channels contribute to beta-adrenoceptor-mediated vasodilator response in rat mesenteric artery, and cyclic adenosine monophosphate (cAMP) might not be involved in regulation of the activity of K-Ca channels.
All Author(s) ListHuang Y, Kwok KH
Journal nameJournal of Cardiovascular Pharmacology
Year1997
Month4
Day1
Volume Number29
Issue Number4
PublisherLIPPINCOTT-RAVEN PUBL
Pages515 - 519
ISSN0160-2446
eISSN1533-4023
LanguagesEnglish-United Kingdom
Keywordsbeta-adrenoceptor; charybdotoxin; glibenclamide; K+ channel; mesenteric artery; rat; vasorelaxation
Web of Science Subject CategoriesCardiac & Cardiovascular Systems; CARDIAC & CARDIOVASCULAR SYSTEMS; Cardiovascular System & Cardiology; Pharmacology & Pharmacy; PHARMACOLOGY & PHARMACY

Last updated on 2020-16-10 at 03:01