Figure 4

Effect of anandamide, pH and Zn²⁺ on TASK-like currents of ED11 atrial myocytes in Cl^- substituted solutions. A: I-V curves averaged from 6 cells showing the effects of pH and anandamide on background K⁺ currents in ED11 atrial myocytes during a 2s depolarizing ramp from -100 to +50 mV. The cells were held at -40 mV and perfused with 140 mM K-aspartate solution. Note TASK-like background K⁺ current had a pronounced inward rectification at pH 8.0. B: The enlarged I-V curves at positive potential. C: The summarized data (n = 6 cells) of the effects of pH and anandamide on TASK-like background K⁺ currents (at -80 mV). The background K⁺ currents at pH 6.4 (filled column), pH 8.0 (blank column) and pH 8.0 in the presence of 3 μM anandamide (back slashed column) are as indicated. The inset panel (a) of Fig. 4C shows pH- (blank column) and anandamide- (filled column) sensitive background K⁺ currents. The anandamide-sensitive currents account for 58% of TASK-like background K⁺ currents. D: Zn²⁺ had no effect on the TASK-like background K⁺ currents. The summarized data (n = 11) of the effects of 100 μM Zn²⁺ on TASK-like background K⁺ currents in ED11 atrial myocytes as indicated. The inset panel b of Fig. 4D shows pH- (blank column) and Zn²⁺- (filled column) sensitive currents at -80 mV in ED11 atrial myocytes.