Journal of Veterinary Medical Science
Online ISSN : 1347-7439
Print ISSN : 0916-7250
ISSN-L : 0916-7250
Mechanisms of NO-Resistant Relaxation Induced by Acetylcholine in Rabbit Renal Arteries
Seong-Chun KWON
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2001 Volume 63 Issue 1 Pages 37-40

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Abstract
The effects of K+ channel blockers and P2Y receptor agonist/antagonist on the vasorelaxation mediated by endothelium-derived hyperpolarizing factor (EDHF) were investigated in the rabbit renal artery. Acetylcholine (ACh, 1 nM-10 μM) induced endothelium-dependent relaxation of arterial rings precontracted with norepinephrine (NE, 1 μM) in a concentration-dependent manner. NG-nitro-L-arginine (L-NAME, 0.1 mM), an inhibitor of NO synthase, partially inhibited the ACh-induced endothelium-dependent relaxation. The ACh-induced relaxation was only partially inhibited by L-NAME whereas combined addition of L-NAME and 30 mM KCl completely inhibited the relaxation. The ACh-induced relaxation observed in the presence of L-NAME was significantly reduced by a combination of iberiotoxin (0.1 μM) and apamin (1 μM), and almost completely blocked by 4-aminopyridine (5 mM). The ACh-induced relaxation was antagonized by P2Y receptor antagonist, cibacron blue (10 and 100 μM) in a concentration-dependent manner. Furthermore, ADPβS, a potent P2Y agonist, induced the endothelium-dependent relaxation, and this relaxation was markedly reduced by either the combination of iberiotoxin and apamin or by cibacron blue alone. In conclusion, ACh may activate the release of ATP from endothelial cells which in turn activates a P2Y receptor on the endothelial cells followed by a release of EDHF, resulting in a vasorelaxation via a mechanism that involves activation of both the voltage-gated K+ channels and the Ca2+-activated K+ channels.
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© 2001 by the Japanese Society of Veterinary Science

この記事はクリエイティブ・コモンズ [表示 - 非営利 - 改変禁止 4.0 国際]ライセンスの下に提供されています。
https://creativecommons.org/licenses/by-nc-nd/4.0/deed.ja
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