Equal open probability with unequal ion-channel relaxation times ($p_{\infty }=a/(a+b),\tau =(a+b{)}^{-1}$)

Multiplying opening and closing rates by the same factor preserves equilibrium open probability but rescales the relaxation and dwell times. At equal opening and closing rates, $p_{\infty }=1/2$ and relaxation is twice as fast as the reciprocal mean individual-state dwell. A two-state constant-voltage model cannot alone produce activation followed by inactivation during a maintained step.