Membrane model of the aortic baroreceptor neuron based upon numerical fits to voltage clamp data

We have undertaken to classify and characterize the essential ion channel currents in aortic baroreceptor neurons of neo-natal and juvenile rat. The isolation of these neurons from the milieu of cellular structures within the nodose ganglia was accomplished using a combination of enzymatic dispersion and fluorescence identification (selected juvenile cells). Whole cell current recordings were performed in our laboratory using a cellular patch clamp technique under voltage-and current-clamp conditions. To date, we have identified a single Na⁺, two Ca²⁺ and four K⁺ channels. A nonlinear system of equations capable of accurately describing the dynamics of these ion channels has been configured according to standard Hodgkin-Huxley formalism. Identification of parameters associated with the system state variables was accomplished using a nonlinear least-squares parameter estimation algorithm. This work has provided a unique compendium of ion channel current descriptions which we have assembled into a comprehensive and physiologically consistent Hodgkin-Huxley-type excitable membrane model of the rat aortic baroreceptor neuron. The preliminary configuration of this model along with examples of mathematical fits to our voltage clamp data and action potential waveforms are presented.