大黄素抑制大鼠离体十二指肠平滑肌的收缩

Emodin inhibits the contraction of isolated duodenum smooth muscle of rats

目的观察大黄素(emodin)对大鼠离体十二指肠平滑肌收缩功能的影响,并探讨其作用机制。方法离体十二指肠标本随机分为7组(n=6):对照组、大黄素剂量组(1、5、10、20μmol·L-1),普萘洛尔(propranolol,PRO)加大黄素组、格列苯脲(glibenclamide,GLI)加大黄素组、NG-硝基-L-精氨酸甲酯(NG-nitroarginine methyl ester,L-NAME)加大黄素组、无钙Krebs-Henseleit(K-H)液对照组及无钙K-H液加大黄素组。采用颈椎离断法处死大鼠并分离其十二指肠,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十二指肠平滑肌的收缩张力(tention,TE)、幅度(amplitude,AM)和频率(frequency,FR)的影响。结果 (1)大黄素能使大鼠离体十二指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<0.01)、格列苯脲(P<0.01)可部分阻断大黄素对十二指肠平滑肌的抑制作用。(3)L-NAME对大黄素所引起的十二指肠平滑肌的抑制作用无影响。(4)氯化钙所引起的十二指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十二指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β受体、开放ATP敏感钾通道、阻断细胞膜上钙离子通道实现。

Aim To investigate the effect of emodin on the contraction of duodenum smooth muscle and its un- derlying mechanisms. Methods Rats were randomly divided into 7 groups （n = 6 in each group） ： control group, emodin group （ 1 , 5, 10, 20 μmol·L^-1） , pro- pranolol （PRO） plus emodin group, glibenclamide （GLI） plus emodin group, NG-Nitro-L-arginine Meth- yl Ester （L-NAME） plus emodin group, calcium free control group and calcium free emodin group. The rats were sacrificed by cervical dislocation and the duode- tnum was isolated. The duodenum segment specimens were mounted on an Organ Bath System with a tension transducer. The effect of emodin on contraction of duo- denum smooth muscle was measured by BL-420E ＋ bio- logical signal processing system and the contraction am- plitude （ AM）, tension （TE） and frequency （FR） were determined. Results （ 1 ） Emodin inhibited the tension and amplitude of duodenum contraction in a dose-dependent manner （P 〈 0. 05, P 〈 0. 01 ） while the frequency was not obviously influenced. （2） Prop- ranolol （P〈0.01） or GLI （P〈0.01） partly abol- ished the inhibitory effect of emodin on duodenum smooth muscle. （3） L-NAME had no obvious effect on the inhibitory effect of emodin. （4） Emodin attenuated the contraction of duodenum smooth muscle induced by calcium chloride application into calcium free K-H so- lution （ P 〈 0. 01 ）. Conclusion Emodin obviously inhibits the amplitude and tension, while it has no in- fluence on the frequency of duodenum smooth muscle contraction in rats. Activation of beta adrenergic recep- tor, open of ATP sensitive potassium channels, and in- hibition of the extracellular calcium influx through cal- cium channels of smooth muscle cell membrane might be involved in the process.