Dai Yun, Liu Jian-Xiang, Li Jun-Xia, Xu Yun-Feng
Department of Gastroenterology, first Hospital of Peking University, Beijing 100034, China.
World J Gastroenterol. 2003 Mar;9(3):557-61. doi: 10.3748/wjg.v9.i3.557.
To investigate the effect of pinaverium bromide, a L-type calcium channel blocker with selectivity for the gastrointestinal tract on contractile activity of colonic circular smooth muscle in normal or cold-restraint stressed rats and its possible mechanism.
Cold-restraint stress was conducted on rats to increase fecal pellets output. Each isolated colonic circular muscle strip was suspended in a tissue chamber containing warm oxygenated Tyrode-Ringer solution. The contractile response to ACh or KCl was measured isometrically on ink-writing recorder. Incubated muscle in different concentrations of pinaverium and the effects of pinaverium were investigated on ACh or KCl-induced contraction. Colon smooth muscle cells were cultured from rats and (Ca(2+))(i) was measured in cell suspension using the Ca(2+) fluorescent dye fura-2/AM.
During stress, rats fecal pellet output increased 61 % (P<0.01). Stimulated with ACh or KCl, the muscle contractility was higher in stress than that in control. Pinaverium inhibited the increment of (Ca(2+))(i) and the muscle contraction in response to ACh or KCl in a dose dependent manner. A significant inhibition of pinaverium to ACh or KCl induced (Ca(2+))(i) increment was observed at 10(-6) mol/L. The IC(50) values for inhibition of ACh induced contraction for the stress and control group were 1.66X10(-6) mol/L and 0.91X10(-6) mol/L, respectively. The IC(50) values for inhibition of KCl induced contraction for the stress and control group were 8.13X10(-7) mol/L and 3.80X10(-7) mol/L, respectively.
Increase in (Ca(2+))(i) of smooth muscle cells is directly related to the generation of contraction force in colon. L-type Ca(2+) channels represent the main route of Ca(2+) entry. Pinaverium inhibits the calcium influx through L-type channels; decreases the contractile response to many kinds of agonists and regulates the stress-induced colon hypermotility.
研究对胃肠道具有选择性的L型钙通道阻滞剂匹维溴铵对正常或冷束缚应激大鼠结肠环行平滑肌收缩活动的影响及其可能机制。
对大鼠进行冷束缚应激以增加粪便颗粒排出量。将每条分离的结肠环行肌条悬挂于含有温热含氧台氏-林格液的组织浴槽中。在墨水记录仪上以等长方式测量对乙酰胆碱（ACh）或氯化钾（KCl）的收缩反应。用不同浓度的匹维溴铵孵育肌肉，并研究匹维溴铵对ACh或KCl诱导收缩的影响。从大鼠分离培养结肠平滑肌细胞，使用钙荧光染料fura-2/AM在细胞悬液中测量细胞内钙离子浓度（[Ca²⁺]i）。
应激期间，大鼠粪便颗粒排出量增加61%（P<0.01）。用ACh或KCl刺激时，应激组肌肉收缩力高于对照组。匹维溴铵以剂量依赖性方式抑制[Ca²⁺]i的升高以及对ACh或KCl的肌肉收缩反应。在10⁻⁶mol/L时观察到匹维溴铵对ACh或KCl诱导的[Ca²⁺]i升高有显著抑制作用。应激组和对照组抑制ACh诱导收缩的半数抑制浓度（IC₅₀）值分别为1.66×10⁻⁶mol/L和0.91×10⁻⁶mol/L。应激组和对照组抑制KCl诱导收缩的IC₅₀值分别为8.13×10⁻⁷mol/L和3.80×10⁻⁷mol/L。
平滑肌细胞内[Ca²⁺]i的增加与结肠收缩力的产生直接相关。L型钙通道是钙离子进入的主要途径。匹维溴铵抑制钙离子通过L型通道内流；降低对多种激动剂的收缩反应，并调节应激诱导的结肠运动亢进。
