Figure 3. Pharmacological properties of K⁺ channels in nucleated patches from OA interneurones.

A-C, K⁺ current traces in control conditions and in the presence of different concentrations of external 4-AP (A), TEA (B), and in 500 nm DTX (C). Recordings from different nucleated patches. D and E, concentration-effect curves for external 4-AP (D) and TEA (E). Continuous curves represent the sum of two Hill equations (Hill coefficients constrained to 1) fitted to the data points. The IC₅₀ values were 24 ± 19 μm (56 ± 16 %) and 2.8 ± 3.2 mm (32 ± 12 %) for 4-AP and 63 ± 36 μm (55 ± 12 %) and 3.2 ± 3.6 mm (28 ± 10 %) for TEA. F and G, K⁺ current traces in control conditions, in the presence of either 0.3 mm 4-AP or 0.5 mm TEA, and in the presence of both blockers. H, fraction of total K⁺ current blocked by TEA, 4-AP, and a combination of both blockers. ○, individual measurements; bars, mean values. Measurements from the same patch are shown connected by lines. Note marked occlusion of the effects. Currents were evoked by test pulses to +70 mV (from a holding potential of −90 mV) in all experiments. Numbers of patches are given in parentheses above data points or bars.