System identification of electrically coupled smooth muscle cells: the passive electrical properties

A system model approach based on a network model is used to investigate the passive electrical properties of coupled smooth muscle cells. This approach makes use of a gradient method of optimization to estimate the passive electrical parameters directly from the magnitude of the input impedance or voltage transfer function of the network model. The need for subjective measurements of parameters and many of the intermediate steps involved in the analysis using the conventional signal model approach are eliminated. The coupling resistance and capacitance are estimated with sound theoretical and mathematical analysis directly from experimental data. The coupling impedance is estimated directly from experimental data. The sensitivities of the network with respect to the resistances, capacitances, and time constants can readily be found. This should provide insight into the passive electrical properties of smooth muscle.