Figure 4.

Astrocytes that are acid loaded in HEPES display pH_i recoveries when exposed to CO₂/HCO₃ ⁻ in the absence of external Cl⁻. As shown in the inset, astrocytes were acid loaded by a brief exposure to a solution containing 20 mM NH₄Cl (a–d ). At c, the astrocytes were exposed to 0.9 mM amiloride for the duration of the experiment. During the indicated period, the cells were then exposed to 5% CO₂/17 mM HCO₃ ⁻ (ef  ). Subsequently, the astrocytes were acid loaded in amiloride and exposed to CO₂/ HCO₃ ⁻ five more times in the absence of Cl⁻ (top). The cells were then returned to the Cl⁻-containing solution and acid loaded one last time.