Validity of applying nonstationary noise analysis to K_Ca2 channel currents. Simulated deactivation currents using the three illustrated gating schemes were subjected to mean-variance analysis to obtain estimates of channel conductance and P(o). Estimates were obtained for three time points in the deactivation 0.3, 10, and 20 ms after the start of the relaxation. These data showed that nonstationary noise analysis can be applied to data obtained from a channel that exhibited two conductance states, such as K_Ca2.2 and K_Ca2.3 channels (see Fig. 2).