FIGURE 6.

Ni²⁺ effects at the single channel level. (A) Shown here are 10 representative and consecutive control sweeps in a one-channel, outside-out patch that were evoked by a 300-ms pulse from −80 mV to 100 mV applied at 0.1 Hz and with [K⁺]_i = 140 mM and [K⁺]_o = 3.5 mM. Data were digitally filtered at 1 kHz. (B) From the same patch as in A, 10 consecutive sweeps evoked with the same voltage protocol but with 0.5 mM Ni²⁺ in the external perfusate. The main effect of Ni²⁺ is to reduce channel availability. Representative all-point amplitude histograms from a different one-channel patch in control and 0.5 mM Ni²⁺-containing perfusate are shown in panels C and D, respectively. A double-Gaussian fit to data gave a mean current in each case of 1.6 pA.