Figure 6.

TWIK-1 gene deletion decreases the relative Cs⁺ to K⁺ permeability of passive conductance. (A) Astrocyte membrane potential (Vm) approaches to Cs⁺ equilibrium potential (E_Cs) in Cs⁺ -based pipette and bath solutions. Switch extracellular 3.5 mM K⁺ to 3.5 mM Cs⁺ resulted in a rapid negative Vm shift in all three genotypes with a net negative shift of around −10 mV at the plateau in 2–3 min. The plateau Vm values at the time point indicated by “*” were summarized in (B). The Cs⁺ established Vm showed a TWIK-1 gene dependent positive shift and the difference between WT and TWIK-1^−/− mice was statistically significant. (C) Representative whole-cell membrane potential recording traces, with bath solutions switched from normal aCSF containing 3.5 mM K⁺ to solutions containing, in sequence, 70 mM K⁺ and 70 mM Cs⁺. E_Cs and E_K are the equilibrium potential of Cs⁺ and K⁺ at 70 mM, respectively. (D) The relative Cs⁺ to K⁺ permeability (P_Cs/P_K) values for three genotypes; the P_Cs/P_K of TWIK-1^−/− mice was significantly lower than that of the TWIK-1. Data are shown as mean ± SEM. Numbers of experiments are given within the bars. ^*p < 0.05, ^**p < 0.01.