Mathematical model to simulate the extracellular myoelectrical activity of the cat colon.

The rationale of this study was to investigate if the bases of generation of the electrical activity of the whole gut are the same. For this reason, we developed a mathematical dipole model, based on the same foundations used to simulate the electrical activity of the human stomach, to generate the electrical activity of the transverse cat colon. The model developed takes into account both the geometry of the transverse colon represented by a cylinder of finite length and the myoelectrical dynamics of the cells. The extracellular electrical activity was simulated by the periodic movement of an annular band polarised by electric dipoles. The simulation not only reproduces both the waveform, amplitude, phase lag and frequency of the ECA and the frequency, duration and periodicity of the ERA but also allows us to reproduce both increases/decreases of frequency, the inversion of phase conditions of the ECA and ERA, and to underline the anatomical and physiological parameters that can modify the ECA amplitude, such as the radius of the colon and the cells' dipole moment density. The simulation also picks up not only the effects of the probes' type (unipolar, bipolar, endoluminal, external) and of their positioning during in vivo experiments made by implanted electrodes to record the ECA and ERA, but also allows us to find both the theoretical best configuration for the surface electrodes and the effects of the distance between the abdominal electrodes and the source of the electrical activity, and of the distance between the electrodes.