Figure 3. Constancy of apparent K⁺/Na⁺ selectivity in TASK-2 after inhibition by extracellular acidification.

Current-voltage relation for a cell expressing TASK-2 at pH 9.0 and 7.0, chosen to yield respectively ∼90 and ∼15% of the maximal activation as judged from complete activity vs. pH curves [20]. The intracellular solution contained 140 mM K⁺ and extracellular bath had 135 mM Na⁺ and 5 mM K⁺. The current-voltage relations were taken from 250 ms-voltage ramps given from the most hyperpolarised voltage. The graph on the right-hand side summarises average E_rev measurements at both pH values in the form of means ± SEMs of 6 experiments. There was no significant difference between E_rev as analysed by paired t-test.