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Figure 3. Arachidonic-acid-activated TREK-1 K+ channel opening. (A) Current traces from an inside-out patch with high-K+ bath solution containing arachidonic acid at various concentrations. The pipette solution was also the high-K+ solution. Vm = 20 mV. (B) Dose-dependent effects of arachidonic acid on the activity of the TREK-1 K+ channel (means ± SD, n = 8). The channel activity is expressed as the percentage of NPo at each concentration relative to NPo at 100 µM of arachidonic acid (%NPo). NPo values were obtained from current recordings in patches where the concentration of arachidonic acid in bath solution was altered between 0 µM and 100 µM by perfusion. Abscissa, common logarithmic scale. (C) %NPo when K+ channel blockers were applied to the bath solution in inside-out patches in which TREK-1 K+ channels had been activated by 10 µM arachidonic acid. Ba2+ at a rather high concentration (3 mM) decreased channel activity. Quinine and quinidine were more effective than Ba2+. Each value was obtained from five inside-out patches (mean ± SD, n = 5). *Significantly different from blocker-free state.
