Ca²⁺ channel currents in dorsal root ganglion neurons of P/Q-type voltage-gated Ca²⁺ channel mutant mouse, rolling mouse Nagoya

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• 作者：Nao Fukumoto^a ; Naoki Kitamura^a ; ^{nakit@muses.tottori-u.ac.jp} ; Kimie Niimi^b ; Eiki Takahashi^b ; Chitoshi Itakura^b ; Izumi Shibuya^a
• 关键词：蠅-ATX ; 蠅-agatoxin IVA ; 4-AP ; 4-aminopyridine ; 蠅-CTX ; 蠅-conotoxin GVIA ; DRG ; dorsal root ganglion ; NMDG ; N-methyl-d-glucamine ; TEA ; tetraethylammonium ; TTX ; tetrodotoxin ; VGCC ; voltage-gated Ca2+ channel
• 刊名：Neuroscience Research
• 出版年：2012
• 期刊代码：53_01680102
• 类别：neu
• 出版时间：July, 2012
• 卷：73
• 期：3
• 页码：199-206
• 文件大小：615 K

摘要

The role of the P/Q-type voltage-gated Ca²⁺ channels (VGCCs) in release of neurotransmitters involved in nociception is not fully understood. Rolling mouse Nagoya (tg^rol), a P/Q-type channel mutant mouse, expresses P/Q-type VGCC whose activation curve has a higher half activation potential and a smaller slope factor than the wild type channel. We previously reported that tg^rol mice showed hypoalgesic responses to noxious stimuli. In this study, we examined the VGCC current in dorsal root ganglion (DRG) neurons by the whole-cell patch-clamp method. Both 蠅-agatoxin IVA (0.1 渭M) and 蠅-conotoxin GVIA (1 渭M) inhibited the VGCC current by about 40-50%in both the homozygous tg^rol (tg^rol/tg^rol) and wild type (+/+) mice. The voltage-activation relationships of the total VGCC current and the 蠅-agatoxin IVA-sensitive component in the tg^rol/tg^rol mice shifted positively compared to the +/+ mice, whereas that sensitive to the 蠅-conotoxin GVIA was not different between the two genotypes. The time constant of activation of the VGCC current at 鈭?0 mV was longer in the tg^rol/tg^rol mice than in the +/+ mice. These changes in the properties of the VGCC in the tg^rol/tg^rol mouse may reduce the amount of the released neurotransmitters and account for the hypoalgesic responses.