Qualitatively, one can see a clear increase in the frequency of such currents from -90 to -85 inV. Just counting events gives a nearly 10-fold increment over this range of potential. A further increment is seen between -85 and -80 mV, but the difference is not as large. When these **data** were quantified with either half amplitude threshold analysis or mean-variance histograms (shown for these **data** in Fig.  2 B), channel open probabilities and open times could be determined. Fig. 3 A shows open probability and open time for these wild-type channels. Consistent with the qualitative estimates described above, the Po curve shows a steep increase in currents between -90 and -85 mV, but then becomes nearly level at more positive potentials. Open times were ~0.1 ms over the whole voltage range, with a gradual increase (roughly e-fold/25 mV) in the range from -90 to -70 inV.