Calculation of ion currents from energy profiles and energy profiles from ion currents in multibarrier, multisite, multioccupancy channel model

This chapter describes the theory of multibarrier channels, illustrating the example of how to find the parameters of a model channel using our programs. Barrier models describe the ion transport through a channel as a series of ion movements from one binding site of the channel to another binding site. The channel can have several binding sites and more than one site can be occupied at any given time. The chapter describes AJUSTE, which is a nonlinear curve-fitting procedure based on the Gauss-Newton method. AJUSTE includes ways of fixing or adjusting any of the parameters of the model and allows constraints to be defined on the allowable values of the parameters. It gives information on the errors of the parameter estimations and parameter correlations. The program is simple, fast, and has provisions to escape from local minima.