Gastrointestinal (Gl) motility patterns depend, in part, on coordination of contractile activity by enteric motor neurons. Enteric excitatory and inhibitory motor neurons contribute to development of appropriate motor patterns in Gl organs. In the colon a prominent motor pattern, known as colonic migrating motor complexes (CMMC) provides propulsive forces for movement of fecal material in the anal direction. At present CMMC are thought to be based on the peristaltic reflex in which local stimuli generate ascending contractions and descending inhibition. This concept has become canonical in neurogastroenterology. In fact there is a 3rd phase of the peristaltic reflex that is poorly understood and infrequently even mentioned in scholariy reviews of peristalsis. Enteric motor neurons activate excitatory and inhibitory neurons and elicit region-dependent contraction and relaxation responses. In most regions of the gut, including the colon, the response to nerve stimulation is followed by a post-stimulus excitatory response (PSR also known as rebound excitation). We have discovered that PSR is actually an extremely important component, if not the main propulsive force, in propagating contractions (i.e. CMMC). CMMC are reduced by only an extent by muscarinic antagonists and not dependent upon excitatory peptides. CMMC are totally eliminated by inhibition of nitric oxide synthase in proximal colon or P2Y1 receptors in distal colon. Thus, CMMC are not dependent upon migrating responses to excitatory nerves but on migrating inhibitory responses coupled to PSR. There are striking similarities in PSR between species, and such a high degree of conservation tends to indicate the importance of PSR in colonic motility. Modifying canons, like the peristaltic reflex, requires careful investigation and determination of the mechanisms driving PSR. Our experiments will reveal the cell-specific steps and signaling pathways responsible for PSR and these findings will provide remarkable new ideas about managing colonic propulsive disorders. We will use reporter strains of transgenic mice for cell studies of PSR, and comparative studies on colonic muscles and whole colonic segments from mice, non-human primates, and human patients to develop a unified and mechanistic concept of PSR and its importance in propulsive movements.

Public Health Relevance

Slow transit constipation is a prevalent health care problem that has been assoicated with loss of interstitial cells of Cajal. In this project we will explore the role of ICC in generating propulsive contraction in the colon and show the consequences of a defect in these cells for nrormal colonic transit.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Program Projects (P01)
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University of Nevada Reno
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Baker, Salah A; Drumm, Bernard T; Saur, Dieter et al. (2016) Spontaneous Ca(2+) transients in interstitial cells of Cajal located within the deep muscular plexus of the murine small intestine. J Physiol 594:3317-38
Durnin, Leonie; Hayoz, Sebastien; Corrigan, Robert D et al. (2016) Urothelial purine release during filling of murine and primate bladders. Am J Physiol Renal Physiol 311:F708-F716
Sanders, Kenton M; Ward, Sean M; Friebe, Andreas (2016) Rebuttal from Kenton M. Sanders, Sean M. Ward and Andreas Friebe. J Physiol 594:1515
Hwang, Sung Jin; Basma, Naseer; Sanders, Kenton M et al. (2016) Effects of new-generation inhibitors of the calcium-activated chloride channel anoctamin 1 on slow waves in the gastrointestinal tract. Br J Pharmacol 173:1339-49
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Sanders, Kenton M; Ward, Sean M; Friebe, Andreas (2016) CrossTalk proposal: Interstitial cells are involved and physiologically important in neuromuscular transmission in the gut. J Physiol 594:1507-9
Sanders, Kenton M (2015) New Molecular Tools to Investigate the Development and Functions of Interstitial Cells of Cajal in the GI Tract. Gastroenterology 149:283-6
Peri, Lauren E; Koh, Byoung H; Ward, Grace K et al. (2015) A novel class of interstitial cells in the mouse and monkey female reproductive tracts. Biol Reprod 92:102
Baker, Salah A; Hennig, Grant W; Ward, Sean M et al. (2015) Temporal sequence of activation of cells involved in purinergic neurotransmission in the colon. J Physiol 593:1945-63
Zhu, Mei Hong; Sung, Tae Sik; O'Driscoll, Kate et al. (2015) Intracellular Ca(2+) release from endoplasmic reticulum regulates slow wave currents and pacemaker activity of interstitial cells of Cajal. Am J Physiol Cell Physiol 308:C608-20

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