An electrical description of the generation of slow waves in the antrum of the guinea-pig.
This paper provides an electrical description of the generation of slow waves in the guinea-pig gastric antrum. A short segment of a circular smooth muscle bundle with an attached network of myenteric interstitial cells of Cajal (ICC-MY) and longitudinal muscle sheet was modelled as three electrical compartments with resistive connexions between the ICC-MY compartment and each of the smooth muscle compartments. The circular smooth muscle layer contains a proportion of intramuscular interstitial cells of Cajal (ICC-IM), responsible for the regenerative component of the slow wave. Hence the equivalent cell representing the circular muscle layer incorporated a mechanism, modelled as a two stage reaction, which produces an intracellular messenger. The first stage of the reaction is proposed to be activated in a voltage-dependent manner as described by Hodgkin and Huxley. A similar mechanism was incorporated into the equivalent cell describing the ICC-MY network. Spontaneous discrete transient depolarizations, termed unitary potentials, are detected in records taken from either bundles of circular smooth muscle containing ICC-IM or from ICC-MY. In the simulation the mean rate of discharge of unitary potentials was allowed to vary with the concentration of messenger according to a conventional dose-effect relationship. Such a mechanism, which describes regenerative potentials generated by the circular muscle layer, also simulated the plateau component of the pacemaker potential in the ICC-MY network. A voltage-sensitive membrane conductance was included in the ICC-MY compartment; this was used to describe the primary component of the pacemaker potential. The model generates a range of membrane potential changes with properties similar to those generated by the three cell types present in the intact tissue.
Edwards
F R
FR
Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia 2601. frank.edwards@anu.edu.au
Hirst
G D S
GD
D000818:Animals; D001683:Biological Clocks / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005769:Gastrointestinal Motility / Q000502:physiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D009130:Muscle, Smooth / Q000502:physiology*; D016065:Myoelectric Complex, Migrating / Q000502:physiology*; D011706:Pyloric Antrum / Q000502:physiology*; D013269:Stochastic Processes