Concentrations of (a) PPi, (b) ATP, and (c) ADP were determined in blood plasma from healthy control (CTRL) and PXE individuals. (d) PlasmaPPi, (e) ATP, (f) AMP, and (g) adenosine were measured in WT and Abcc6−/− mice. Data represent the mean ± standard error of the mean of the indicated number of plasma samples. #P < 0.05, ###P < 0.005. ADO, adenosine; AMP, adenosine monophosphate; ATP, adenosine triphosphate; CTRL, control; PPi, pyrophosphate; PXE, pseudoxanthoma elasticum; WT, wild type.