汉防己甲素抑制气道神经兴奋引起的平滑肌收缩反应

INHIBITORY EFFECTS OF TETRANDRINE ON SMOOTHMUSCLE CONTRACTION INDUCED BY ACTIVATION OF THE AIRWAY NERVES IN VITRO

汉防己甲素（汉甲，０．３～３０μｍｏｌ·Ｌ－１）浓度依赖地抑制豚鼠离体气管片和支气管条平滑肌由电场刺激所引起的收缩反应。实验结果显示：汉甲对气道感觉神经Ｃ类纤维兴奋所致收缩的抑制作用强于对胆碱能神经兴奋所致收缩的抑制；上述抑制作用在颈部气管片明显强于胸腔内气管片和支气管条平滑肌。Ｐ＜０．０１（ｂ、ｃ组与ａ组等浓度点的比较）汉甲抑制各组气道平滑肌Ⅰ、Ⅱ相收缩反应的半效抑制量参见附表。附表汉甲抑制豚鼠离休气道平滑肌Ⅰ相和Ⅱ相收缩反应的半效抑制量（ＩＣ５０±９５％可信限）３讨论豚鼠离体气管和支气管标本内神经兴奋时引起平滑肌收缩反应，Ⅰ相收缩是胆碱能神经末梢兴奋引起，Ⅱ相收缩则是感觉神经Ｃ类纤维兴奋所致［１］。汉甲对ＥＦＳ引起的平滑肌收缩的Ⅰ、Ⅱ相反应均有浓度依赖的抑制作用，然而其抑制作用的强度有差别。图１、２的量效曲线和附表资料均显示，汉甲对气道标本Ⅰ相收缩的抑制作用远弱于对Ⅱ相收缩的抑制强度，需较高浓度的汉甲才对１相反应有明显抑制作用，两者的ＩＣ５０值也显示同样的差别。说明汉甲对豚鼠气道中Ｃ类神经纤维兴奋效应的抑制作用明显强于对胆碱能神经兴奋效应的抑制。已有实验证明汉甲通过抑制豚鼠气管平滑肌细胞膜的钙离子通道，?

The electrical field stimulation(EFS)inducad the nervous endings activation of the guineapig airway, and the contration of the smooth muscles thus occurred. Tetrandrine (0.3～30 μmol·L-1) inhibited the EFS-evoked contraction of the smooth muscles in a concentration dependent manner. According to the IC50 and the dose-effect curves, the inhibitory effects on the airway contraction induced by the sensory C-fibers activation were more significant than the airway contraction induced by the activation of the cholinergic nerve endings; the inhibitory effects on the contraction of the tracheas in the neck induced by the activation of the C-fibers were the most significant in the three airway preparation groups (tracheas in the neck, tracheas in the chest, and bronchi of guinea-pigs).