Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/26435
Title: Mitochondrial monoamine oxidase-A-mediated hydrogen peroxide generation enhances 5-hydroxytryptamine-induced contraction of rat basilar artery
Authors: Poon, CCW
Seto, SW
Au, ALS
Zhang, Q
Li, RWS
Lee, WYW
Leung, GPH
Kong, SK
Yeung, JHK
Ngai, SM
Ho, HP
Lee, SMY
Chan, SW
Kwan, YW
Keywords: 5-hydroxytryptamine
Basilar artery
Mitochondrial reactive oxygen species
Monoamine oxidases
Spontaneously hypertensive rats
Issue Date: 2010
Publisher: Wiley-Blackwell
Source: British journal of pharmacology, 2010, v. 161, no. 5, p. 1086-1098 How to cite?
Journal: British journal of pharmacology 
Abstract: BACKGROUND AND PURPOSE We evaluated the role(s) of monoamine oxidase (MAO)-mediated H 2O 2 generation on 5-hydroxytryptamine (5-HT)-induced tension development of isolated basilar artery of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. EXPERIMENTAL APPROACH Basilar artery (endothelium-denuded) was isolated for tension measurement and Western blots. Enzymically dissociated single myocytes from basilar arteries were used for patch-clamp electrophysiological and confocal microscopic studies. KEY RESULTS Under resting tension, 5-HT elicited a concentration-dependent tension development with a greater sensitivity (with unchanged maximum tension development) in SHR compared with WKY (EC 50: 28.4 ± 4.1-nM vs. 98.2 ± 9.4-nM). The exaggerated component of 5-HT-induced tension development in SHR was eradicated by polyethylene glycol-catalase, clorgyline and citalopram whereas exogenously applied H 2O 2 enhanced the 5-HT-elicited tension development in WKY. A greater protein expression of MAO-A was detected in basilar arteries from SHR than in those from WKY. In single myocytes and the entire basilar artery, 5-HT generated (clorgyline-sensitive) a greater amount of H 2O 2 in SHR compared with WKY. Whole-cell iberiotoxin-sensitive Ca 2+-activated K + (BK Ca) amplitude measured in myocytes of SHR was approximately threefold greater than that in WKY (at +60-mV: 7.61 ± 0.89-pA.pF -1 vs. 2.61 ± 0.66-pA.pF -1). In SHR myocytes, 5-HT caused a greater inhibition (clorgyline-, polyethylene glycol-catalase- and reduced glutathione-sensitive) of BK Ca amplitude than in those from WKY. CONCLUSIONS AND IMPLICATIONS 5-HT caused an increased generation of mitochondrial H 2O 2 via MAO-A-mediated 5-HT metabolism, which caused a greater inhibition of BK Ca gating in basilar artery myocytes, leading to exaggerated basilar artery tension development in SHR.
URI: http://hdl.handle.net/10397/26435
ISSN: 0007-1188
EISSN: 1476-5381
DOI: 10.1111/j.1476-5381.2010.00941.x
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