Test of the noise-induced nonequilibrium kinetic focusing of voltage-gated ion channels

It has been postulated [1] that voltage-gated ion channels can be focused into specific conformational states by application of fluctuating voltages, such as dichotomous noise. We conducted an experimental test on Shaker K+ channels. We applied the dichotomous noise, reproducing the conditions in [1] as close as physiologically feasible. We also varied the frequency and the amplitude of the dichotomous noise within a certain range. We observed that in some cases, for intermediate noise frequencies (1-2 kHz) and large amplitudes, the probability for intermediate states in the Markov model of the ion channel gating kinetics can be significantly increased above the maximal value for any static voltages. However, so far the scale of the focusing effect observed experimentally is smaller than the numerical simulations predict. \newline [1]. M.M.Millonas, D.R.Chialvo, Phys.Rev.Lett. 76, 550 (1996)