American Physiological Society, American Journal of Physiology - Gastrointestinal and Liver Physiology, 1(308), p. G1-G11
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Background. Narrow muscle strips have been extensively used to study intestinal contractility. Larger specimens, from laboratory animals, have provided detailed understanding of mechanisms that underlie patterned intestinal motility. Despite progress in animal tissue, investigations of motor patterns in large, intact specimens of human gut, ex vivo, have been sparse. In this study, we tested whether neurally-dependent motor patterns could be detected in isolated specimens of intact human ileum. Methods. Specimens (n = 14; 7-30cm long) of terminal ileum were obtained with prior informed consent from patients undergoing colonic surgery for removal of carcinomas. Preparations were set up in an organ bath with an array of force transducers, a fiber-optic manometry catheter, and a video camera. Spontaneous and distension-evoked motor activity was recorded and the effects of lidocaine, which inhibits neural activity, were studied. Results. Myogenic contractions (ripples) occurred in all preparations (6.17±0.36 per minute). They were of low amplitude and formed complex patterns by colliding and propagating in both directions along the specimen at anterograde velocities of 4.1±0.3mm/s and retrogradely at 4.9±0.6 mm/s. In five specimens, larger amplitude clusters of contractions were seen (Discrete Clustered Contractions) which propagated aborally at 1.05±0.13 and orally 1.07±0.09mm/s. These consisted of 2-8 phasic contractions that aligned with ripples. These motor patterns were abolished by addition of lidocaine (0.3mM). The ripples continued unchanged in the presence of this neural blocking agent. Conclusions. These results demonstrate that both myogenic and neurogenic motor patterns can be studied in isolated specimens of human small intestine.