DIETARY L-ARGININE PREVENTS FETAL GROWTH RESTRICTION IN RATS

OBJECTIVE: Alterations in maternal plasma arginine concentration accom pany normal pregnancy. Nitric oxide is synthesized from L-arginine and influences fetal growth, We hypothesized that L-arginine would influe nce fetal growth and hypoxia-induced uricemia in a maternal hypoxia-in duced fetal growth restriction model. STUDY DESIGN: Fetal growth on da y 21 of gestation was assessed in timed pregnant Wistar rats with or w ithout exposure to maternal hypobaric hypoxia. Animals exposed to hypo xia received either no supplement or supplementation of drinking water with 0.2% L-arginine, 2% L-arginine, or 2% glycine. On day 21 of gest ation, fetuses were delivered by hysterotomy and fetal and placental w eights were obtained. Maternal and fetal plasma were assayed for uric acid as an index of tissue hypoxia. Xanthine oxidase and xanthine dehy drogenase, precursors of uric acid and reactive oxygen species, were a ssayed in maternal tissue. Results were analyzed by analysis of varian ce with correction for multiple comparisons. RESULTS: Exposure of rats on normal diets to hypoxia resulted in a 30% reduction in fetal weigh ts. L-Arginine, 2% or 0.2%, prevented the reduction in fetal weight (p < 0.0001). Isocaloric and isonitrogenous supplementation with glycine did not influence hypoxia-induced fetal growth restriction. CONCLUSIO N: L-Arginine, but not glycine, ameliorates maternal hypoxia-induced f etal growth restriction in the rat.