THE MECHANICS OF RELAXATION IN THE COLON
Martin Buist, Jing Wui Yeoh, Alberto Corrias
National University of Singapore, Singapore
Despite a growing wealth of experimental data, our understanding of the biomechanics of the gastrointestinal tract remains far from complete. The colon forms part of the lower gastrointestinal tract and gives rise to a variety of motility disorders. It is also relatively accessible such that biomechanical data can be obtained in vivo. As well as producing contractions to provide propulsion, of equal importance is the ability of the colon to relax, something that is controlled to a large degree by inhibitory enteric neurotransmission. Here, we have developed computational models to study the influence of enteric inhibitory neuromuscular transmission on the electrophysiology of human colonic smooth muscle cells. We have constructed a biophysically based human colonic smooth muscle cell (hCSMC) model which can reproduce slow wave activity, along with a model to describe the role of a novel platelet-derived growth factor receptor alphapositive cell in the purinergic inhibitory neural control of colonic motility. Third, we have extended the hCSMC model to incorporate a description of the nitrergic intracellular regulatory pathway. Finally, we integrated both inhibitory neuromuscular transmissions to reconstruct the experimentally observed biphasic inhibitory junction potential and examined the mechanical consequences using an active mechanics model. These models provide the basis for a more detailed understanding of the neurogenic inhibitory modulation of human colonic motility in health and disease.