Figure 3.

Measurement of intrinsic intracellular buffering power. (a) Experiment on a WT CA1 neuron. The CA1 neuron was first bathed with HEPES buffer containing Na⁺, and then switched to one without Na⁺ to block the Na⁺-dependent ion exchange. The cell was subsequently exposed to 10 mM, 5 mM, 2.5 mM, and 0 mM NH₃/NH₄⁺, respectively. The cell responded by gradually reducing pH_i. (b) Relation of intrinsic intracellular buffering power (β_I) as a function of pH_i. Data are summarized from 7 experiments on WT mice and 10 experiments on NHE1 mutant mice. Each β_I was calculated within pH_i intervals of 0.2.