Table 1.

Effect of Sepiapterin on Cellular Biopterin Production in Vascular Endothelial Cells

Condition	Total biopterin (pmol/mg)	BH4 (pmol/mg)
HUVEC (DMSO)	2.2 ± 0.13	0.7 ± 0.07
Sep	45.8 ± 18.8*	9.6 ± 4.6*
LY	2.1 ± 0.9	0.79 ± 0.06
Sep+LY	52.1 ± 22.0	10.1 ± 4.3

HUVEC were incubated with Sep (10 μmol/L) for 30 minutes with or without pretreatment of LY (10 μmol/L) for 1 hour or the vehicle control (DMSO). Cell pellets were harvested, and biopterin levels were determined by high-performance liquid chromatography using both acid-base oxidation with fluorometric detection. Values shown are the means ± SEM of two triplicate determinations (n = 6, 

^*P < 0.05 vs. vehicle control, or LY determined by ANOVA).