Fig. 3.

Influence of Na⁺ and HCO₃⁻ upon I-V relationships for human vs. rabbit NBCe1-A. Oocytes were injected with either H₂O (A), cRNA encoding human NBCe1-A-EGFP (B), or cRNA encoding rabbit NBCe1-A (C). I-V relationships were obtained by 2-electrode voltage clamp while the cells were sequentially exposed to a Na⁺-free ND96 solution that contained 96 mM NMDG⁺ in place of 96 mM Na⁺, a 33-mM HCO₃⁻ solution in the continued absence of Na⁺, and finally a 33-mM HCO₃⁻ solution containing 96 mM Na⁺. Note that the circles in A are artificially offset by +2 mV, and the diamonds by −2 mV, from the squares to make all data sets visible. Averaged slope conductances measured between −20 and +20 mV for 6 cells are shown in D, in which the results of certain paired one-tailed t-tests are shown as horizontal bars (*P < 0.05). The composition of solutions used in this protocol is shown in Table 3.