The spontaneous mechanical activity of the circular smooth muscle of the rabbit colon in vitro
The spontaneous mechanical activity of the circular smooth muscle of the rabbit colon in vitro
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DOI：
10.1016/j.phrs.2008.01.002
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发表时间：
2008-02-01
影响因子：
9.3
通讯作者：
Gharzouli, Kamel
中科院分区：
文献类型：
--
作者：
Benabdallah, Hassiba;Messaoudi, Dahla;Gharzouli, Kamel
离体家兔近端、中段和远端结肠的自发性机械活动表现为两种类型的收缩：低振幅、高频率的阶段性收缩和高振幅、低频率的巨大收缩（GCs）。这两种收缩模式在不同地区没有差异。对中结肠巨大收缩的神经控制的研究给出了以下结果。(1)（2）新斯的明抑制乙酰胆碱酯酶后，GC转变为时相性收缩，而神经节烟碱受体激动剂二甲基苯基哌嗪则在短时间内使其消失;（3）NO合成酶的底物L-精氨酸（L-arginine）使GC的持续时间延长，但不影响GC的振幅;（4）亚甲蓝抑制鸟苷酸环化酶可使GC发生时相性收缩;（5）用非选择性阻断剂四乙铵或用更有选择性的apamin敏感性Ca 2+依赖性K+通道阻断剂阻断K+通道，dequalinium，增加静息张力和收缩幅度下降，而开放ATP敏感的K+通道的二氮嗪取消任何节律性收缩活动。这些数据表明，GC的幅度和频率是由内源性NO释放激活鸟苷酸环化酶控制的，随后cGMP的形成反过来激活Ca ~（2+）依赖性K ~+通道的开放。胆碱能输入似乎是负责的静息张力，这种张力的增加是倾向于强加的相位收缩模式的组织。(C)2008爱思唯尔有限公司保留所有权利。
The spontaneous mechanical activity of the proximal, middle and distal colon of the rabbit shows in vitro two types of contractions: phasic contractions with low amplitude and high frequency, giant contractions (GCs) with high amplitude and low frequency. Both patterns of contractions did not present differences according to the region. Investigations on the neural control of giant contractions in the middle colon gave the following results. (1) GCs are insensitive to muscarinic antagonism by atropine and ganglionic blockade by hexamethonium; (2) GCs are converted into phasic contractions following the inhibition of acetylcholinesterase by neostigmine, and are abolished for a short period by dimethyl-phenyl-piperazinium, a ganglionic nicotinic receptor agonist; (3) application of L-arginine, the substrate of nitric oxide (NO) synthase prolonged the duration of GCs without affecting their amplitude; sodium nitroprusside, a donor of NO, reduced both the amplitude and frequency of GCs; (4) inhibition of guanylate cyclase by methylene blue converted GCs into phasic contractions; (5) blockade of K+ channels with the non-selective blocker, tetraethylammonium, or with the more selective apamin-sensitive Ca2+-dependent K+ channels blocker, dequaliniun, increased the resting tone and decreased the amplitude of contractions; whereas opening of ATP-sensitive K+ channels by diazoxide abolished any rhythmic contractile activity. These data taken together suggest that the amplitude and frequency of GCs are controlled by the endogenous release of NO which activates guanylate cyclase, the subsequent formation of cGMP activates in turn the opening of Ca2+-dependent K+ channels. The cholinergic input seems to be responsible of the resting tone, and an increase of this tone is prone to impose the phasic contractions pattern to the tissue. (C) 2008 Elsevier Ltd. All rights reserved.