Figure 1.

Increased PTH and FGF-23 levels are associated with reduced renal Npt2a and Npt2c expression in AC6^−/− mice with free access to food and water. (A) In contrast to WT mice, significantly higher urinary phosphate/creatinine, PTH, and FGF-23 levels were detected in AC6^−/− mice, whereas plasma 1,25 (OH₂)D levels were suppressed. No significant differences between AC6^−/− and WT mice were detected in plasma phosphate or calcium concentrations. (B) Analysis of Npt2a and Npt2c abundances in membrane fractions of renal cortex by Western blotting; densitometric analysis of Western blots was performed using β-actin expression as a reference. Increased urinary phosphate in AC6^−/− mice is associated with lower amounts of Npt2a and Npt2c compared with WT. For physiologic parameters, n=9–11/genotype; for protein abundance, n=5/genotype. *P<0.05 versus WT.