Kuizenga MH, Sia TC, Dodds KN, Wiklendt L, Arkwright JW, Thomas A, Brookes SJ, Spencer NJ, Wattchow DA, Dinning PG, Costa M. Neurally mediated propagating discrete clustered contractions superimposed on myogenic ripples in ex vivo segments of human ileum. Am J Physiol Gastrointest Liver Physiol 308: G1-G11, 2015. First published November 13, 2014; doi:10.1152/ajpgi.00230.2014.-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. Specimens (n ϭ 14; 7-30 cm 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 fiberoptic 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. Myogenic contractions (ripples) occurred in all preparations (6.17 Ϯ 0.36/min). 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 Ϯ 0.3 mm/s and retrogradely at 4.9 Ϯ 0.6 mm/s. In five specimens, larger amplitude clusters of contractions were seen (discrete clustered contractions), which propagated aborally at 1.05 Ϯ 0.13 mm/s and orally at 1.07 Ϯ 0.09 mm/s. These consisted of two to eight phasic contractions that aligned with ripples. These motor patterns were abolished by addition of lidocaine (0.3 mM). The ripples continued unchanged in the presence of this neural blocking agent. These results demonstrate that both myogenic and neurogenic motor patterns can be studied in isolated specimens of human small intestine. small intestine; motor patterns; enteric nervous system; myogenic; neurogenic PROPULSION AND MIXING OF INTESTINAL CONTENTS along the digestive tract are essential for normal digestion. The motor patterns underlying these functions are due to the coordinated contractions and relaxations of the smooth muscle layers of the intestine. The internal circular smooth muscle layer and the external longitudinal smooth muscle layer are controlled by two main mechanisms. Myogenic activity is driven by the nonneural pacemaker cells, the interstitial cells of Cajal. Neurogenic control is mediated by circuits in the enteric nervous system. These two types of activity combine to generate the motor patterns that mix and propel luminal content (14,29). Most of our understanding of these mechanisms has been derived from animal studies. Although the basic functions of the gastrointestinal tract are similar between human and animals, there are si...