Figure 2. Effect of PI(4,5)P₂ scavengers on TASK-2-mediated currents.

(A) Time course of K⁺ currents (means ± SEM) recorded at 0 mV in HEK-293 cells expressing TASK-2 after gaining access into the cells with pipette solutions containing 100 (n = 3), 200 (n = 4) or 300 (n = 9) μM Neomycin. The recordings were made in the presence of 1 mM intracellular ATP. The control curve shown as a dashed line is from Fig. 1E. (B) Recording from an excised inside-out patch of membrane taken from a HEK-293 cell over-expressing TASK-2. The patch was held at −60 mV in the presence of 1 mM intracellular ATP. During the times indicated by the bars intracellular pH was decreased from 7.4 to 5.5, or 300 μM Neomycin or 100 μM TPeA were added. (C) Recording from an excised inside-out patch obtained under the same conditions as in (B), except that the concentration of neomycin in the solution bathing the intracellular aspect of the membrane was increased stepwise from 5 to 500 μM as shown. The graph shows the means of four experiments that gave an average IC₅₀ for neomycin of 23.4 ± 2.7 μM (mean ± SEM, n = 4).