Simulated currents containing one, two, three channels, and mean times of each open level. (A) Simulated currents containing one (top), two (middle) and three (bottom) independent channels. We used a two state model (Scheme 1) with α = 250 s-1, and β = 400 s-1 to simulate the currents. The simulated currents were sampled at 100 kHz and filtered with a digital filter of 10 kHz. The mean closed and unitary current amplitude set to 0 and 1 pA respectively. We set the standard deviation for closed and open level of 0.1 and 0.3 pA to mimic the large open channel noise of P2X2 receptors. Oi represents the nth open level for multiple channel currents. (B) The mean times of each open level from 5 s of simulated data.