Neural regulation of slow waves and phasic contractions in the distal stomach: a mathematical model

Abstract

Objective: Neural regulation of gastric motility occurs partly through the regulation of gastric bioelectrical slow waves and phasic contractions. The interaction of the tissues and organs involved in this regulatory process is complex. We sought to infer the relative importance of cellular mechanisms in inhibitory neural regulation of the stomach by enteric neurons and the interaction of inhibitory and excitatory electrical field stimulation. 
Approach: A novel mathematical model of gastric motility regulation by enteric neurons was developed and scenarios were simulated to determine the mechanisms through which enteric neural influence is exerted. This model was coupled to revised and extended electrophysiological models of gastric slow waves and smooth muscle cells. 
Main results: The mathematical model predicted that regulation of contractile apparatus sensitivity to intracellular calcium in the smooth muscle cell was the major inhibition mechanism of active tension development, and that the effect on slow wave amplitude depended on the inhibition of non-specific cation currents more than the inhibition of calcium-activated chloride current (kiAno1 = 0.33 vs kiNSCC = 0.77). The model predicted that the interaction between inhibitory and excitatory neural regulation, when applied with simultaneous and equal intensity, resulted in an inhibition of contraction amplitude almost equivalent to that of inhibitory stimulation (79% vs 77% decrease), while the effect on frequency was overall excitatory, though less than excitatory stimulation alone (66% vs 47% increase).
Significance: The mathematical model predicts the effects of inhibitory and excitatory enteric neural stimulation on gastric motility function, as well as the effects when inhibitory and excitatory enteric neural stimulation interact. Incorporation of the model into organ-level simulations will provide insights to the pathological mechanisms underpinning gastric functional disorders, as well as allow for in silico testing of the effects of clinical neuromodulation protocols for treatment of these disorders.