Effect of clustered ion channels along an unmyelinated axon.

In most unmyelinated axons, ion channels are distributed uniformly along the axon to facilitate stable propagation of action potentials. In this case, the conduction in the axon is continuous, and the excitability along the membrane is constant. Some experimental papers show that ion channels also locate in clusters in some unmyelinated axons. In this paper, we investigate theoretically the effect of clustered ion channels along unmyelinated axon. We mainly focused on two aspects: the propagation efficiency and the propagation speed. Our results show that localization of potassium ion channels is beneficial for increasing propagation efficiency and propagation speed of action potentials; however, localization of sodium ion channels is advantageous to the propagation efficiency only when axonal parameters are in a specific range.