A Bubble Model for the Gating of Kv Channels

TL;DR

This paper introduces a bubble model combined with a PNP system to simulate Kv channel gating, capturing delays and stochastic behaviors consistent with experimental data.

Contribution

It presents a novel coupled bubble and PNP model that explains gating delays and stochasticity in Kv channels, validated against experimental observations.

Findings

The model reproduces the delay in channel opening.

Predicted ensemble currents match experimental data.

Varying holding potential captures Cole-Moore delay.

Abstract

Voltage-gated Kv channels play fundamental roles in many biological processes, such as the generation of the action potential. The gating mechanism of Kv channels is characterized experimentally by single-channel recordings and ensemble properties of the channel currents. In this work, we propose a bubble model coupled with a Poisson-Nernst-Planck (PNP) system to capture the key characteristics, particularly the delay in the opening of channels. The coupled PNP system is solved numerically by a finite-difference method and the solution is compared with an analytical approximation. We hypothesize that the stochastic behaviour of the gating phenomenon is due to randomness of the bubble and channel sizes. The predicted ensemble average of the currents under various applied voltages across the channels is consistent with experimental observations, and the Cole-Moore delay is captured by varying the holding potential.