大黄素对大鼠离体空肠平滑肌收缩的影响

目的：观察大黄素（emodin）对大鼠离体空肠平滑肌收缩功能的影响，并探讨其作用机制。方法：大鼠离体空肠标本随机分为7组（n=6）：对照组，大黄素剂量组（1，5，10，20μmol／L），普萘洛尔（PRO）加大黄素组，格列苯脲（GLI）加大黄素组，NG-基-L厂精氨酸甲酯（1．NAME）加大黄素组，无钙K-H液对照组及无钙K-H液大黄素组。采用颈椎离断法处死大鼠并分离其空肠，将肠段标本与张力换能器相连并置于氧饱和的K-H液中。采用BL-420E＋生物信号采集处理系统记录大鼠空肠平滑肌的收缩张力（TE），幅度（AM）和频率（FR）的影响。结果：①大黄素能使大鼠离体空肠平滑肌的收缩张力和幅度明显下降，且呈剂量依赖性（P〈0．05，P〈0．01）；对频率无明显影响。②普萘洛尔（P〈0．05）、格列苯脲（P〈0．01）可部分阻断大黄素对空肠平滑肌的抑制作用。③L．NAME对大黄素所引起的空肠平滑肌的抑制作用无影响。④氯化钙所引起的空肠平滑肌收缩可被大黄素所抑制（P〈0．01）。结论：大黄素能明显减弱大鼠离体空肠平滑肌的收缩张力和收缩幅度，对收缩频率无影响。这种作用可能是通过兴奋肾上腺素8受体、兴奋ATP敏感钾通道、阻断细胞膜上钙离子通道实现。

The effect of emodin on the contraction of isolated jejunum smooth muscle of rats

Objective： To investigate the effect of emodin on the contraction of jejunum smooth muscle and its underlying mechanisms. Methods： Rats were randomly divided into 7 groups （ n = 6 ） ： control group, emodin group （ 1, 5, 10, 20 wnot/L）, propranolol （PRO） pins emodin group, glibenclamide （GLI） plus emodin group, NG-Nitro- L-arginine Methyl Ester （L-NAME） plus emodin group, calcium free con- trol group and calcium free emodin group. The rats were sacrificed by cervical dislocation and the small intestine was isolated. The jejunum segment specimens were mounted on an Organ Bath System with a tension transducer. The effect of emodin on contraction of jejunum smooth muscle was measured by BL-420E＋ biological signal processing system and the amplitude （AM）, tension （TE） and frequency （FR） of con- traction were determined. Results： （~） Emodin inhibited the tension and amplitude of jejunum smooth muscle contraction in a dose-dependent manner （ P 〈0.05, P 〈0.01） while the frequency was not obviously influenced. （~） PRO （ P 〈0.05） or GLI （ P 〈 0.01） partly abolished the inhibitory effect of emodin on jejunum smooth muscle. QL-NAME had no obvious effect on the inhibitory effect of emodin. （~） Emodin at- teunated the contraction of jejunum smooth muscle induced by calcium chloride application into calcium free K-H solution （ P 〈 0.01）. Con- clusion： Emodin obviously inhibits the amplitude and tension, while has no influence on the frequency of jejunum smooth muscle contraction in rats. Activation of beta adrenergic receptor, open of ATP sensitive potassium channels, and inhibition of the extracellular calcium influx through calcium channels of smooth muscle cell membrane might be involved in the process.