Figure 4.

Data summary for the ΔpH_S measurements. The bars summarize the results of a larger number of experiments, like those shown in Figure 2. a Maximum pH_S excursions evoked by CO₂ exposure. Upon exposure to a flowing solution of 5% CO₂/33 mM HCO₃^–, H₂O-injected control oocytes become more alkaline. However, in the oocytes expressing RhAG, RhBG, or RhCG, the alkalinization—as shown by a larger (ΔpH_S)_CO2 value—is greater than that of H₂O injected oocytes. b Maximum pH_S excursions evoked by NH₃ exposure. When the same oocyte is exposed to 0.5 mM NH₃/NH₄⁺, the magnitude of the acidification (ΔpH_S)_NH3 in the RhAG-, RhBG-, or RhCG-expressing oocytes is also greater than in H₂O-injected control oocytes. For RhBG_D178N and the RhCG_D177N the (ΔpH_S)_CO2 and (ΔpH_S)_NH3 values (not shown) are not statistically different from the H₂O injected controls. We performed Student’s t-test (two tails) for statistical comparisons.