Figure 6.

Thiazide-sensitive J_Cl and thiazide-sensitive Na⁺-dependent Cl⁻/HCO₃⁻ exchanger (NDCBE; Slc4a8) abundance do not increase markedly with intercalated cell (IC) Nedd4–2 gene ablation. (A) Cl⁻ absorption, J_Cl, was measured in cortical collecting ducts (CCDs) from IC Nedd4–2 null mice (n=13) and wild-type (WT) littermates (n=8) with 100 μM hydrochlorothiazide (HCTZ) or vehicle (Veh) added to the perfusate. Solid lines indicate experiments where Veh was present in the first period and HCTZ was added in the second period. The dashed lines show the reverse order (i.e., HCTZ present in period 1 and then removed in period 2). B compares thiazide-sensitive J_Cl in CCDs from both groups. C shows NDCBE protein abundance in plasma membrane-enriched preparations from the renal cortex of IC Nedd4–2 null mice and WT littermates. Each lane was loaded with a protein sample from a different mouse; (D) 15 μg proteins were loaded per gel lane, and equal loading was confirmed by parallel Coomassie-stained gels. The anti-NDCBE antibody recognized a band at 130 kD. Densitometric values were normalized to the mean for the Cre (−), WT littermates.