Fig. 6.

Single-channel Cl⁻ currents from inside-out patches excised from rat β-cells. Pipette and bath solutions contained 150 mM NMDG-Cl; pipette contained also 10 μM nifedipine and 10 μM glibenclamide. Sampling rate, 5 kHz; 1-kHz filter setting; 100-Hz final digital filtration. Filled pipette resistance, 20 MΩ. Dotted lines indicate zero-current or single-channel levels. a Representative recordings. Single-channel currents are activated by 1 μM Ca²⁺ in the bathing solution. b Representative number of events–amplitude histograms at +60 and +80 mV. Single-channel amplitudes were obtained from Gaussian fit. The scale bars indicate 250 events. c Current–voltage relationship of single-channel Cl⁻ currents activated by Ca²⁺. A single-channel conductance (γ) of 8.37 ± 0.15 pS was calculated from a linear fit (r = 0,989, P < 0.0001) on all the points (n = 65: +100 mV, n = 6; +80 mV, n = 7; +60 mV, n = 28; +40 mV, n = 7; −40 mV, n = 3; −60 mV, n = 6; −80 mV, n = 5; −100 mV, n = 3 experiments performed on six preparations of rat dispersed islet cells). d Time course of channel activity before and during exposure to 1 μM Ca²⁺ in the absence of inhibitors (n = 5), in the presence of T-AO1 100 μM (n = 7) and in the presence of TA 100 μM (n = 6) in the pipette solution at +60 mV. Upper panel: representative recordings in presence (or not) of the inhibitors. Lower panel: mean NPo (±SEM) values, i.e., the product of the number of channels in a patch (N) by the open probability (Po), calculated for 2 min, after 15-s stimulation with Ca²⁺. The n experiments were performed on two preparations of rat dispersed islet cells. Kruskal–Wallis test on d, P < 0.001, *P < 0.05, ***P < 0.001 vs. control (Mann–Whitney-type tests with Dunn–Bonferroni correction)