Figure 6.

Removing external Na⁺ elicits a larger and faster pH_i decrease when astrocytes are exposed to CO₂/HCO₃ ⁻ rather than to HEPES. We replaced external Na⁺ with Li⁺ when the cell was exposed to a HEPES-buffered solution (ab) and a 5% CO₂/17 mM HCO₃ ⁻-buffered solution (e–g).