FIGURE 6.

Effects of different CaSR modulators and ion channel blockers on HCO₃⁻ fluxes in SCBN cells. A, control time course of pH_i changes induced by NH₄Cl in Na⁺-free/HCO₃⁻ solution. Treatment of cells with 30 mm NH₄Cl in the solution caused the pH_i first to increase and then to decrease when the NH₄Cl was washed out. The cells remained acidic, and the pH_i was relatively stable in Na⁺-free/HCO₃⁻ solution, but the pH_i began to recover when the cells were returned to NaCl/HCO₃⁻ solution (Na⁺). B, genistein-induced HCO₃⁻ fluxes through CFTR channels. The time course of pH_i changes in SCBN cells was similar to the control in A. However, after the NH₄Cl was washed out, genistein (Gen, 50 μm) was added to the cells acidified in Na⁺-free/HCO₃⁻ solution, and the pH_i began to recover, but further recovery occurred after adding back NaCl/HCO solution (Na⁺). C, spermine-induced HCO₃⁻ fluxes through CFTR channels. The time course of pH_i changes was similar to B, but spermine (Sper, 1 mm) was added to the cells acidified in Na⁺-free/HCO₃⁻ solution. D, summary data showing the effects of different CaSR modulators and ion channel blockers on HCO₃⁻ fluxes in SCBN cells. CFTR_inh-173 (10 μm), 2-APB (100 μm), and Gd³⁺ (0.5 mm) were applied to the experiments. Values are expressed as mean ± S.E. of 40–50 cells for each group. **, p < 0.01 versus control (Con) in A; ##, p < 0.01 versus their corresponding activators in B and C.