FIGURE 6.
RhCG is required for apical NH3 permeability of cortical collecting duct cells. Cortical collecting ducts were isolated from kidneys of Rhcg+/+, Rhcg+/−, and Rhcg−/− mice after 2 days of HCl loading, and intracellular pH was monitored with BCECF. 20 mm NH4Cl was applied with the luminal perfusate. A, pHi recording from CCD exposed to a luminal NH4Cl pulse in Rhcg+/+ and Rhcg+/− CCD. Exposure to NH4Cl caused a rapid alkalinization corresponding to NH3 entry into cells. The initial slopes (ΔpHi/Δt) of the alkalinization phase were measured, and the amount of NH3 titrated into NH4+ was finally calculated based on intracellular buffering power. B, bar graph summarizing the amount of titrated NH3 during luminal NH4Cl pulses (n = 8–12 tubules/genotype). *, p < 0.05; NS, not significant.