Shafik A
Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Egypt.
Anat Rec. 1997 Nov;249(3):405-8. doi: 10.1002/(SICI)1097-0185(199711)249:3<405::AID-AR12>3.0.CO;2-S.
During our study of the defecation mechanism, we found that the external anal sphincter contracted not only upon rectal inflation but also upon deflation. As this reflex relationship was reproducible, it was studied to elucidate its clinical significance in the light of its function.
A catheter with a condom at its end was introduced into the rectum of 16 healthy volunteers (mean age 45.2 years). The EMG response of the external anal sphincter to rapid rectal inflation and deflation was studied by means of a concentric needle electrode inserted into the muscle. The procedure was repeated in eight subjects after sphincter infiltration with xylocaine or saline.
The external sphincter contracted twice on rectal distension: once on inflation and another time on deflation. The amplitude increased and latency decreased with increasing rectal inflation, while neither was affected on deflation. The anesthetized sphincter did not respond, while the saline-infiltrated sphincter responded to rectal distension.
The deflation reflex functions to interrupt or terminate the act of defecation. It may prove of diagnostic significance in defecation disorders.
在我们对排便机制的研究中，我们发现肛门外括约肌不仅在直肠扩张时收缩，在直肠收缩时也会收缩。由于这种反射关系具有可重复性，因此我们根据其功能对其临床意义进行了研究。
将末端带有避孕套的导管插入16名健康志愿者（平均年龄45.2岁）的直肠。通过插入肌肉的同心针电极研究肛门外括约肌对直肠快速扩张和收缩的肌电图反应。在8名受试者的括约肌用利多卡因或生理盐水浸润后重复该过程。
直肠扩张时，外括约肌收缩两次：一次在扩张时，另一次在收缩时。随着直肠扩张程度增加，收缩幅度增大，潜伏期缩短，而在直肠收缩时两者均无变化。麻醉后的括约肌无反应，而注入生理盐水的括约肌对直肠扩张有反应。
直肠收缩反射的作用是中断或终止排便行为。它可能在排便障碍的诊断中具有重要意义。
