A Barrier Kinetic Mapping Unit: Application to Ionic Transport in Gastric Smooth Muscle

Abstract

A model has been developed to characterize the ionic basis of the shape of the electrical control activity (ECA) observed in gastric smooth muscle. The model uses barrier kinetics to describe the underlying ionic transport mechanisms responsible for the gastric ECA. The transmission coefficient parameter, which has been given little importance in the past, plays a major role in our model. It represents the gating and kinetics of the different channels. The model compares well with the Goldman‐Hodgkin‐Katz current equations for the sodium, calcium, and potassium channels. The model illustrates the importance of the calcium pump in maintaining the resting membrane potential and shows how the waveshape is influenced by the ratio of free to total intracellular calcium concentration. The effects of potassium accumulation and calcium on the waveform were also investigated. In the fundus of the stomach, where there are no voltage oscillations, the potassium channels were found to be more important than the other channels in maintaining the resting membrane potential.