Figure 2. Role of Slc23a1 in ascorbate renal reabsorption and tight control.

(A) Urine ascorbate as a function of plasma ascorbate concentrations. Plasma and urine samples were obtained at the same time in female and male Slc23a1^+/+, Slc23a1^+/–, and Slc23a1^–/– mice (n = 6–18). Ascorbate concentrations were determined by HPLC as described in Methods. (B and C) Ascorbate fractional excretion and clearance. Plasma and urine was obtained at the same time from individual female (B) and male (C) mice (n = 6 per sex and genotype). Ascorbate, creatinine, and inulin were analyzed, and fractional excretion and clearance values were calculated as described in Methods. Differences between inulin clearances for genotypes of each sex were not statistically significant. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001 versus respective control.