Figure 3.

The effect of pyrophosphate (PPi) on the chronic (pseudoxanthoma elasticum–like) calcification phenotype of Abcc6^−/− mice. Abcc6^−/− mice were injected daily for 16 to 20 weeks with either saline (white bars) or a PPi solution at 224 μmol/kg per day (eg, 100 mg/kg per day) (black bars). Injections started either at weaning before the onset of ectopic calcification in vibrissae and continued daily for 16 weeks or were initiated at 6 months of age (after onset) when whiskers calcification is well developed, and continued for 20 weeks. For comparison purposes, vibrissae calcification of untreated Abcc6^−/− mice is shown (gray bars). The number of mice per group is shown. Data are expressed as means ± SEM. ^∗∗∗P < 0.001. WT, wild-type.