摘要
本文旨在研究硫化氢(hydrogen sulfide, H2S)前体L-半胱氨酸对大鼠结肠动力的影响,以阐明其对结肠收缩的调节作用及机制。采用免疫组织化学染色和免疫印迹实验检测内源性H2S合成酶胱硫醚-γ-裂解酶(cystathionine-γ-lyase, CSE)和胱硫醚-β-合成酶(cystathionine-β-synthase, CBS)在大鼠近端结肠的表达情况;采用生理记录仪检测结肠平滑肌收缩活动的变化;利用膜片钳实验检测结肠平滑肌细胞离子通道电流。结果显示,CBS和CSE在大鼠近端结肠黏膜层、平滑肌层及肌间神经丛均有表达;L-半胱氨酸以浓度依赖的方式抑制近端结肠纵行平滑肌收缩,H2S合成酶抑制剂氨基氧乙酸(aminooxyacetateacid,AOAA)和炔丙基甘氨酸(propargylglycine, PAG)孵育纵行平滑肌后,L-半胱氨酸半最大效应浓度(concentration for 50%of maximal effect, EC50)相比对照组显著下降(P <0.05);而L-半胱氨酸对结肠环形肌收缩具有抑制和促进双重调节作用,AOAA和PAG预处理可阻断其对环形肌的兴奋作用;H2S外源性供体Na HS在低浓度时促进平滑肌细胞L型钙通道开放(P <0.01),而在高浓度时抑制L型钙通道电流(ICa,L)(P <0.05);与Na HS不同,L-半胱氨酸浓度依赖性抑制ICa,L (P <0.01);Na HS抑制大电导钙激活钾电流(IBKCa),而L-半胱氨酸对IBKCa无明显作用。以上结果提示,L-半胱氨酸对大鼠结肠平滑肌收缩具有潜在双重调节作用,其中抑制作用由L型钙通道介导,而促进作用可能是由内源性生成的H2S介导。
The purpose of the present study is to investigate the effect of L-cysteine on colonic motility and the underlying mechanism.Immunohistochemical staining and Western blot were used to detect the localization of the H2S-generating enzymes cystathionine-β-synthase(CBS)and cystathionine-γ-lyase(CSE).Organ bath system was used to observe the muscle contractile activities.Whole-cell patch-clamp technique was applied to record ionic channels currents in colonic smooth muscle cells.The results showed that both CBS and CSE were localized in mucosa,longitudinal and circular muscle and enteric neurons.L-cysteine had a dual effect on colonic contraction,and the excitatory effect was blocked by pretreatment with CBS inhibitor aminooxyacetate acid(AOAA)and CSE inhibitor propargylglycine(PAG);L-cysteine concentration-dependently inhibited L-type calcium channel current(ICa,L)without changing the characteristic of L-type calcium channel(P<0.01);In contrast,the exogenous H2S donor NaHS increased ICa,L at concentration of 100μmol/L,but inhibited ICa,L and modified the channel characteristics at concentration of 300μmol/L(P<0.05);Furthermore,L-cysteine had no effect on large conductance calcium channel current(IBKCa),but NaHS significantly inhibited IBKCa(P<0.05).These results suggest that L-cysteine has a potential dual effect on colonic smooth muscle and the inhibitory effect might be directly mediated by L-type calcium channel while the excitatory effect might be mediated by endogenous H2S.
作者
全晓静
邹百仓
秦斌
戴菲
罗和生
王进海
QUAN Xiao-Jing;ZOU Bai-Cang;QIN Bin;DAI Fei;LUO He-Sheng;WANG Jin-Hai(Department of Gastroenterology,Second Affiliated Hospital of Xi’an Jiaotong University,Xi’an 710004,China;Department of Gastroenterology,Renmin Hospital of Wuhan University,Wuhan 430060,China)
出处
《生理学报》
CAS
CSCD
北大核心
2020年第3期299-307,共9页
Acta Physiologica Sinica
基金
This work was supported by the National Natural Science Foundation of China(No.81770540).
关键词
L-半胱氨酸
硫化氢
离子通道
膜片钳
大鼠
L-cysteine
hydrogen sulfide
ion channel
patch-clamp technique
rat
