四甲基吡嗪促进远端结肠黏膜分泌HCO_3^-的机制探讨

Investigation of underlying mechanisms in effect of tetramethylpyrazine on HCO_3^- secretion of distal colonic mucosa

目的探讨四甲基吡嗪(Tetramethylpyrazine,TMP)促进远端结肠黏膜分泌HCO3-的相关机制。方法采用Ussing小室装置,在去除细胞外Cl-的情况下,观察TMP对大鼠远端结肠黏膜短路电流的影响。结果基底膜侧加入TMP引起短路电流的升高,但是顶端膜预先加入DPC(Cl-通道抑制剂)后,TMP的作用降低大约60%(P<0.01)。基底膜侧预先加入DIDS(Na-HCO3-共转运体阻断剂)后,TMP的作用无显著改变(P>0.05)。基底膜侧和顶端膜均预先加入乙酰唑胺(碳酸酐酶阻断剂)后,TMP的作用降低大约45%(P<0.05)。结论 TMP可以促进远端结肠黏膜分泌HCO3-,这一作用是通过细胞内的碳酸酐酶和顶端膜的Cl-通道来实现的。

Objective To investigate the underlying cellular mechanisms in the effect of tetramethylpyrazine on HCO3-secretion of distal colonic mucosa.Methods Using Ussing chamber,the effects of TMP on short-circuit current（Isc） were observed in the absence of extracellular Cl-.Results Basolateral application of TMP induced the increase in Isc of colonic mucosa.Pretreatment of DPC,a kind of Cl-channel blocker,and acetazolamide,the inhibitor of carbonic anhydrase,decreased TMP-induced Isc by about 60% and 45% respectively（P0.05）.However,pretreatment of DIDS,a blocker of Na-HCO3-cotransporter,failed to alter the TMP-induced Isc（P0.05）.Conclusions Intracellular carbonic anhydrase and apical Cl-channel were involved in the TMP-induced colonic HCO3- secretion.