Etiology of irritable bowel syndrome

为了深入了解肠易激综合征（IBS）的病理生理，我们在体内同时测量了正常和IBS结肠的运动性和经上皮电位差（PD）。正常结肠：1)除直肠有周期性运动活动（振幅10-30 cm H_2O，频率3-4周期/s，持续时间10-30 min，间隔70-100 min）外，结肠收缩多为散发性；2)个体间PD差异较大（10 ~ 50mV），但个体间横结肠和直肠结肠段PD差异不大；3)在约30%的总事件中，收缩与PD升高有关，可能反映了Cl分泌的激活；4)结肠壁膨胀导致PD升高。肠易激综合征结肠：1)肠蠕动与正常结肠无明显差异；腹泻型肠易激综合征的ZTPD非常高，而便秘型肠易激综合征的ZTPD相当小。此外，通过体外大鼠远端结肠，我们证明了结肠壁的膨胀通过激活粘膜下神经元导致粘膜Cl分泌增加。利用现有方法的进一步研究将揭示运动和Cl分泌紊乱在IBS病理生理中的重要作用。

To get insight into Pathophysiology of irritable bowel syndrome (IBS) we measured simultaneously motility and transepithelial potential difference (PD) in normal and IBS colon in vivo. In normal colon: 1) Colonic contractions are mostly sporadic except in the rectum where a periodic motor activity (amplitude, 10-30 cm H_2O; frequency, 3-4 cycle/s; duration, 10-30 min; interval, 70-100 min) was observed; 2)PD was highly variable among individuals (10--50mV) but was not different in the colonic segments between the transverse colon and rectum in each individual; 3)In about 30% of total events, contraction was associated with an increase in PD, presumably reflecting the activation of Cl secretion; 4)Distention of colonic wall caused an increase in PD. In IBS colon: 1)Motility was not noticeably different from that in the normal colon; ZTPD was extremely high for diarrhea-type IBS whereas it was rather small for constipation-type IBS. In addition, using rat distal colon in vitro, we demonstrated that distention of the colonic wall causes an increase in mucosal Cl secretion through the activation of submucosal neurons. Further investigation utilizing the present methods would reveal critical roles of disordered activation of motility and Cl secretion for the pathophysiology of IBS.