No abstract

A model of electrical activity in the somatic membrane of dorsal root ganglion (DRG) neurons of the rat was constructed from the experimental data about magnitudes and kinetic parameters of individual ion currentS. Numerical experimentS indicated several types of response to a short depolarizing pulse of the membrane potential, depending on the densities of voltage-dependent ion currents, and also distinct role of different currents in generation of repetitive responses. It was shown that activation of low-threshold calcium current and inactivating potassium current are most significant for the generation of repetitive responses to a single pulse.

The data on the kinetics of voltage-dependent K § conductances studied in the somatic membrane of rat dorsal root ganglion (DRG) neurons were used in a model of repetitive generation of action potentials. Brief currents depolarizing the membrane from the potentials negative to -75 mV elicited more than one action potential, if a proper balance of outward and inward currents occurred in the final phase of repolarization. Low voltage-activated (LVA) Ca 2 § current was the most significant inward current in this balance, opposed by outward K § and leakage currents. Three types of voltage-activated K + currents found in DRG neurons played distinct roles in generation of repetitive action potentials. Inactivating D-type K* current directly influenced this generation, being a major outward current in the above-mentioned balance. Transient A-type K § current was largely inactivated in the final phase, but mediated generation of repeated spikes through inactivation of LVA Ca 2 § currents in the declining phase of an action potential. Non-inactivating delayed rectifier K* current was not involved in generation of repetitive spikes, because the membrane potential only briefly exceeded its activation threshold. The effect of Ca2 § -pendent K § currents was also negligible at short modeling lifespans, but its growth in the course of continuous oscillatory firing due to accumulation of Ca 2 § was possible.