Musial F, Crowell M D
Section of Cybernetical Psychology and Psychobiology, Heinrich-Heine-University, Düsseldorf, Germany.
Physiol Behav. 1995 Dec;58(6):1145-8. doi: 10.1016/0031-9384(95)02058-6.
Chronic changes in rectal compliance and perception are often associated with constipation, but the mechanisms responsible for these changes are not known. These studies evaluated the dynamic response of the rectal wall to distention and, in a separate investigation, the influence of adaptive relaxation on perception thresholds. In Study 1, seven healthy volunteers were evaluated using a computer-controlled barostat to maintain continuous isobaric distention of the rectum at urge threshold over a 25-min period. Changes in intrabag volume were evaluated at minutes 1, 5, and 25. Study 2 investigated changes in perception thresholds with different interstimulus intervals (30 s vs. 60 s) in 16 healthy subjects. Pressure was incremented in steps of 2 mmHg up to discomfort threshold. The mean intrabag volume, pressure, and the compliance index for the first and second 5-s intervals were compared to the last 5 s interval. Statistical analyses were performed using the Wilcoxon Sign-Rank test with Bonferonni corrections. Study 1 showed a significant relaxation of the rectal wall in response to balloon distention with volumes consistently increasing from minute 1 to minute 25. Study 2 showed a significant change in the compliance index at the threshold for moderate urge and intense urge during the 60-s distention that resulted from progressive relaxation of the rectal wall. Study 1 showed an adaptive response of the rectum to distention. Study 2 confirmed these findings and implied a role for this adaptive response in the determination of rectal sensory thresholds.
直肠顺应性和感知的慢性变化常与便秘相关，但导致这些变化的机制尚不清楚。这些研究评估了直肠壁对扩张的动态反应，并且在另一项研究中，评估了适应性舒张对感知阈值的影响。在研究1中，使用计算机控制的恒压器对7名健康志愿者进行评估，以在25分钟内将直肠维持在排便阈值的持续等压扩张状态。在第1、5和25分钟评估袋内体积的变化。研究2调查了16名健康受试者在不同刺激间隔（30秒与60秒）下感知阈值的变化。压力以2 mmHg的步长递增直至不适阈值。将前两个5秒间隔和最后一个5秒间隔的平均袋内体积、压力和顺应性指数进行比较。使用带有Bonferonni校正的Wilcoxon符号秩检验进行统计分析。研究1显示，随着袋内体积从第1分钟到第25分钟持续增加，直肠壁对球囊扩张有显著舒张反应。研究2显示，在60秒扩张期间，直肠壁逐渐舒张导致中度便意和强烈便意阈值时顺应性指数有显著变化。研究1显示直肠对扩张有适应性反应。研究2证实了这些发现，并暗示这种适应性反应在确定直肠感觉阈值中起作用。
