NSNA of macroscopic mHCN2-EGFP currents. (A, top) Voltage protocol used for channel activation and deactivation. (bottom) 6 representative traces from 100 repeatedly collected traces. (B) Current variance over the complete time course of a single episode. (C) Current variance versus mean current amplitude. Red, parabola fit of the macroscopic current part. Green, parabola fit of the tail current part. (D) Normal residual after curve fit for macroscopic current (corresponding to the red trace in C). Results: single-channel current, −0.298 pA (−130 mV); single-channel conductance, 2.29 pS; total number of channels, 8,715; Po, 75.5%. Adjusted R², 0.934. (E) Normal residual after curve fit for tail current (corresponding to the green trace in C). Results: single-channel current, −0.114 pA (−40 mV); single-channel conductance, 2.86 pS; total number of channels, 4,707; Po, 88.4%. Adjusted R², 0.963.