H2 control strategy for Na ion channels on the neural cellular membrane

Abstract

The channel gating process of neural cells is the first step of neural information transmission. We have proposed a kinetic model for state transitions for a sodium (Na) ion gating channel under H2 control. The channel state consisted of an open state, three closed but activated states, and four inactivated but not closed states. This modeling was based strictly on molecular biological observations. Three charged amino acid helixes of the specific subunits of the Na channel hole act as activating gates. Another helix of the subunit having membrane voltagesensing properties behaves as an inactivating particle that invades the Na channel hole after membrane depolarization. This particle blocks the free movements of the three activating gates and inactivates the Na channel gating function. In total there are eight channel states, which consist of four inactivated states, three closed states, and one open state. We expressed the transitions among these states by eight linear differential equations using the law of conservation. For the control principle, the channel system is always exposed to a biological mimetic that is a false transmitter and competes for the channel sites with Na ions. Hence, we regarded such biological agencies as noises in the system that disturb the effective transmission of information, i.e., rapid transitions through the channel gating systems. The physiological Na gating is understood to minimize influences from the disturbing noises on the transition of the channels states, and we have proposed the H2 control principle. The computed results of temporal changes in the amount of channel species per unit membrane area showed rapid changes and then termination. This behavior was strongly dependent on the membrane potential. Our modeling could describe the rapid excitation and resetting of the Na ion channel gating function of the neural system. These results strongly reflect the digital nature of the neural system. The present investigation could be used to evaluate the function of neural systems that minimizes the influences of noises on the information transmission process by the transitions of the Na ion channel gating state.