Figure 6.

Sensitivity of astrocyte passive conductance and cloned TWIK-1 and TREK-1 K⁺ channels to extracellular pH. A, B, Representative voltage ramp-induced whole-cell current traces of TWIK-1 and TREK-1 in transfected CHO cells at pH 7.4 (black traces) and pH 6.0 (gray traces). Washout traces are shown as the dashed lines. C, Comparison of effects of extracellular low pH, pH 6.0, on astrocyte passive conductance and expressed TWIK-1 and TREK-1 channels. Whole-cell currents at test voltage +20 mV in the pH 6.0 bath solution (gray bars) are compared with the normalized corresponding values in the pH 7.4 bath solution (open bars) (n = 5–7 for each data point; *p < 0.005). D, Representative whole-cell current traces recorded from an astrocyte in pH 7.4 and pH 6.0 bath solutions. Calibration: 10 ms, 1 nA. E, The mean current–voltage relationships for astrocyte recordings obtained in pH 7.4 (open square) and pH 6.0 (gray square) bath solutions (n = 6). The pooled data show that pH 6.0 significantly inhibited 27% of the outward passive currents at +20 mV of test voltage.