  The non-selective voltage activated cation channel from the human red cells,
which is activated at depolarizing potentials, has been shown to exhibit
counter-clockwise gating hysteresis. We have analyzed the phenomenon with the
simplest possible phenomenological models by assuming $2\times 2$ discrete
states, i.e. two normal open/closed states with two different states of ``gate
tension.'' Rates of transitions between the two branches of the hysteresis
curve have been modeled with single-barrier kinetics by introducing a
real-valued ``reaction coordinate'' parameterizing the protein's conformational
change. When described in terms of the effective potential with cyclic
variations of the control parameter (an activating voltage), this model
exhibits typical ``resonant effects'': synchronization, resonant activation and
stochastic resonance. Occurrence of the phenomena is investigated by running
the stochastic dynamics of the model and analyzing statistical properties of
gating trajectories.
