A new double-chamber model of ion channels. Beyond the Hodgkin and Huxley model.
This paper proposes a new double-chamber model (DCM) of ion channels. The model ion channel consists of a series of three pores alternating with two chambers. The chambers are net negatively charged. The chamber's electric charge originates from dissociated amino acid side chains and is pH dependent. The chamber's net negative charge is compensated by cations present inside the chamber and in a diffuse electric layer outside the chamber. The pore's permeability is constant independent of time. One pore of the sodium channel and one of the potassium channel is a voltage-sensing pore. Due to the channel's structure, ions flow through the pores and chambers in a time-dependent manner. The model reproduces experimental voltage clamp and action potential data. The current flowing through a single sodium channel is less then one femtoampere. The DCM is considerably simpler then the Hodgkin and Huxley model (HHM) used to describe the electrophysiological properties of an axon. Unlike the HHM, the DCM can explain refractoriness, anode break excitation, accommodation and the effect of pH and temperature on the channels without additional parameters. In the DCM, the axon membrane shows repetitive activity depending on the channel density, sodium to potassium channel ratio and external potassium concentration. In the DCM, the action potential starts from 'hot spot areas' of higher channel densities and a higher sodium to potassium channel ratio, and then propagates through the whole axon.
Dołowy
Krzysztof
K
Department of Biophysics, Warsaw Agricultural University - SGGW, Rakowiecka 26/30, 02-528 Warszawa, Poland.
D000200:Action Potentials; D001369:Axons / Q000502:physiology; D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000502:physiology*; D008954:Models, Biological; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000502:physiology; D013696:Temperature
D007473:Ion Channels; D015221:Potassium Channels; D015222:Sodium Channels; D012964:Sodium; D011188:Potassium