| Gastrointestinal motility is controlled by the appearance of a rhythmic electrical activity called the electrical control activity (ECA). It is possible to represent the ECA as the product of a population of coupled oscillators with the oscillators being the spontaneously electrically oscillating smooth muscle cells of the GI tract. Electrical coupling of the cells has been proposed both by gap junctions and electrical fields. Gap junctions have been shown to be too sparse in certain instances to account for the noted level of coupling. It is, therefore, hypothesized that in these regions there is an appreciable amount of field coupling.;The electric field method of coupling is investigated quantitatively by use of computer models. Using Green's Theorem and boundary element techniques, the field strength produced by a single smooth muscle cell in an infinite conducting medium is examined. The modelling procedure allowed completely arbitrary geometry as well as control of propagation velocity, conductivities, origin of wave propagation and voltage waveform. The effects of all these parameters on the extracellular fields were calculated. The results indicate that field coupling can produce a level of coupling which is sufficient to cause frequency pulling of gastrointestinal oscillators. |
