Acute 1,25D treatment does not impair PTH signaling. (A) PTHR1 mRNA expression in proximal tubular cells. (B) Circulating PTH levels. (C) Urinary cAMP/creatinine ratio. Data represent the mean ± SEM. *P < 0.05 vs WT; #P < 0.05 vs Hyp control mice. Vehicle-treated wild-type mice (WT), vehicle-treated Hyp mice (HypC), and Hyp mice treated with 1,25D for 1 (HypD1h) or 18 (HypD18h) h. (D) Immunoprecipitation of NaPi2a with anti-NHERF1 from renal cortical lysates of WT mice treated with vehicle, PTH alone, or PTH and 1,25D. NaPi2a and NHERF1 protein input. Data are representative of that obtained from three independent replicates per treatment group.