Fig. 6.

Influence of sulfite, in the absence of HCO₃⁻, upon I-V relationships for human vs. rabbit NBCe1-A. Experiments similar to those shown in Fig. 3 except that the cells were sequentially exposed to 1) a Ca²⁺-free ND96 solution; 2) a modified a Ca²⁺-free ND96 solution that contained 33 mM sulfite in place of 59.4 mM Cl⁻; and finally 3) a Ca²⁺-free 33-mM HCO₃⁻ solution that, compared with the preceding solution, contained 33 mM HCO₃⁻ + 33 mM Cl⁻ in place of 33 mM sulfite. Note that, in addition to A, the squares in B and C are artificially offset by +2 mV from the circles to make all data sets visible. The composition of solutions used in this protocol is shown in Table 6. Horizontal bars, *P < 0.05.