Modelling of Ca2+-activated chloride current in tracheal smooth muscle cells

Stimulation of airway myocytes by contractile agents such as acetylcholine (ACh) activates a Ca2+-activated Cl- current (I(ClCa)) which may play a key role in calcium homeostasis of airway myocytes and hence in airway reactivity. The aim of the present study was to model I(ClCa) in airway smooth muscle cells using a computerised model previously designed for simulation of cardiac myocyte functioning. Modelling was based on a simple resistor-battery permeation model combined with multiple binding site activation by calcium. In order to validate the model, a combination of equations, used to mimic [Ca2+]i response to ACh stimulation, were incorporated into the model. The results indicate that the model developed in this article accounts for experimental recordings and electrophysiological characteristics of this current in airway smooth muscle cells, with parameter values consistent with those calculated from experimental data. Such a model may thus be used to predict I(ClCa) functioning, though additional experimental data from airway myocytes would be useful to more accurately determine some parameter values of the model.