[Rate of excitation propagation in a reduced Hodgkins-Huxley model. II. Slow relaxation of the sodium current].
The influence of sodium current activation on the value of nerve excitation conduction velocity is investigated on the basis of Hodgkin-Huxley model. The potassium activation and sodium inactivation are considered as slow processes which do not develop to an appreciable extent in the region of conduction velocity formation. The system of equations was derived and solved analytically after neglecting the dependency of sodium relaxation time on potential; the approximation of steady-state sodium activation was also used with the help of Hevyside function. The algebraic equation for conduction velocity was obtained; its solution has a simple analytical form in two limits of rapid and slow sodium current relaxation. The comparison with the experimental data has shown that at not very high temperatures the slow (compared to the potential dynamics) sodium current relaxation approximation is more appropriate. The dependency of impulse velocity on capacitance and conductance of the fiber was analyzed.
D004594:Electrophysiology; D008959:Models, Neurological; D009431:Neural Conduction; D012964:Sodium / Q000502:physiology*
D012964:Sodium
O skorosti rasprostraneniia vozbuzhdeniia v redutsirovannoĭ modeli Khodzhkina--Khaksli. II. Medlennaia relaksatsii natrievogo toka