Figure 10.

Removing external Na⁺ elicits a depolarization that is inhibited by DIDS or by removing 20% CO₂/68 mM HCO₃ ⁻. (A) Effect of removing Na⁺ on the V_m of astrocytes exposed to a “high” CO₂/HCO₃ ⁻ solution. We replaced external Na⁺ with Li⁺ when the cell was exposed to a HEPES-buffered solution (ab) and a 20% CO₂/68 mM HCO₃ ⁻-buffered solution (ef  ). In a separate experiment on an astrocyte exposed to 400 μM DIDS, we replaced external Na⁺ with Li⁺ in the presence of 20% CO₂/68 mM HCO₃ ⁻ (e ' f '  ). (B) The magnitude of the depolarization plotted as a function of V_m for 14 astrocytes in which external Na⁺ was removed in either HEPES (○) or 20% CO₂/68 mM HCO₃ ⁻ (•). Some data points represent the average depolarization elicited by removing external Na⁺ more than once in a single experiment.