Coupled Markov chain model: characterization of membrane channel currents with multiple conductance sublevels as partially coupled elementary pores.

A parameterized Markov chain model is developed to represent the characteristics of channel currents that either are the superposition of many single channels or show multiple conductance sublevels. The simplified model takes the form of a set of binary chains that are interdependent according to a simple lumped coupling parameter. When varied, this parameter realizes a range of behaviors from tight coupling to complete independence. Other model parameters describe the intrinsic characteristics of the binary chains. An identification procedure for the model parameters is developed based on hidden Markov modeling ideas but incorporating a novel parameter estimation. The usefulness of the model in analyzing certain types of data is demonstrated with examples of real channel currents.