Figure 6. Effects of bubbling on arachidonic acid concentration in solution.

A, whole-cell current recordings (at –50 mV from standard voltage ramps) show that arachidonic acid (10 μm) caused a marked activation of TREK-1 under hypoxic conditions (3% oxygen) when it was added to the solution after bubbling with nitrogen (AA not bubbled), but caused little or no activation of TREK-1 currents when the arachidonic acid was added first and then the solution bubbled (AA bubbled). B, arachidonic acid (10 μm) remained in solution when stirred (^) but was rapidly removed from solution if the solution was bubbled with nitrogen (•), oxygen (▴) or air (▪) (see Methods). The arachidonic acid can be shown to have been deposited on the glassware because when the bottle was rinsed with ethanol 85 ± 9% of the arachidonic acid could be recovered after bubbling with nitrogen (see Recovery data point in B).