A theoretical analysis of anatomical and functional intestinal slow wave re-entry

• Published in: Journal of theoretical biology Vol. 425; pp. 72 - 79
• Main Authors: Du, Peng, O'Grady, Gregory, Cheng, Leo K.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 21.07.2017
• Subjects: Electrophysiological Phenomena - physiology; Electrophysiology; Gastrointestinal Motility - physiology; Humans; Intestinal dysrhythmia; Intestines - anatomy & histology; Intestines - physiology; Models, Biological; Monodomain; Multi-scale model; Electrophysiology; Multi-scale model; Intestinal dysrhythmia; Monodomain
• ISSN: 0022-5193; 1095-8541
• DOI: 10.1016/j.jtbi.2017.04.021

•Anatomical and functional re-entry activities are modeled.•Re-entry are maintained via entrainment at a higher frequency than the baseline.•Slow wave refractory periods play a key role in the termination of re-entry.•Secondary stimulus can be used to terminate re-entry. Intestinal bioelectrical slow waves are a key regulator of intestinal motility. Peripheral pacemakers, ectopic initiations and sustained periods of re-entrant activities have all been experimentally observed to be important factors in setting the frequency of intestinal slow waves, but the tissue-level mechanisms underpinning these activities are unclear. This theoretical analysis aimed to define the initiation, maintenance, and termination criteria of two classes of intestinal re-entrant activities: anatomical re-entry and functional re-entry. Anatomical re-entry was modeled in a three-dimensional (3D) cylindrical model, and functional rotor was modeled in a 2D rectangle model. A single-pulse stimulus was used to invoke an anatomical re-entry and a prolonged refractory block was used to invoke the rotor. In both cases, the simulated re-entrant activities operated at frequencies above the baseline entrainment frequency. The anatomical re-entry simulation results demonstrated that a temporary functional refractory block would be required to initiate the re-entrant activity in a single direction around the cylindrical model. The rotor could be terminated by a single-pulse stimulus delivered around the core of the rotor. In conclusion, the simulation results provide the following new insights into the mechanisms of intestinal re-entry: (i) anatomical re-entry is only maintained within a specific range of velocities, outside of which the re-entrant activities become either an ectopic activity or simultaneous activations of the intestinal wall; (ii) a maintained rotor entrained slow waves faster in the antegrade direction than in the retrograde direction. Simulations are shown to be a valuable tool for achieving novel insights into the mechanisms of intestinal slow wave dysrhythmia.