SIMULATION AND CALCULATION OF THE CONTRIBUTION OF HYPERPOLARIZATION-ACTIVATED CYCLIC NUCLEOTIDE-GATED CHANNELS TO ACTION POTENTIALS

The hyperpolarization-activated cyclic nucleotide-gated (HCN) channel, which mediates the influx of cations, has an important role in action potential generation. In this article, we describe the contribution of the HCN channel to action potential generation. We simulated several common ion channels in neuron membranes based on data from rat dorsal root ganglion cells and modeled the action potential. The ion channel models employed in this paper were based on the Markov model. After modifying and calibrating these models, we compared the simulated action potential curves under the presence and absence of an HCN channel and calculated that the proportional contribution of the HCN channel in the potential recovery phase was 33.39%. This result indicates that the HCN channel is critical in assisting membrane potential recovery from a hyperpolarized state to a resting state. Furthermore, we showed how the HCN channel modifies the firing of the action potential using mathematic modeling. Our results indicated that although the loss of the HCN channel made recovery of the membrane potential more difficult from the most negative point to resting in comparison with the control, the firing rate of the action potential increased in certain circumstances. We present a novel explanation for the HCN channels' mechanism in neuron action potential generation using mathematical models.