title: Materno-fetal transport of creatine in the rat.
abstract: The transfer of 14C-creatine to the rat fetus was studied following continuous i.v. infusion into the mother. In the presence of a relatively constant maternal plasma 14C-creatine concentration, creatine was accumulated by the chorioallantoic placenta and visceral yolk sac to concentrations higher than that found in maternal or fetal plasma. The ability of the extraembryonic membranes to accumulate creatine changed during gestation; nevertheless, these membranes concentrated creatine against a gradient throughout the period studied (14-22 days of gestation). Neither 14C-creatine nor 14C-urea were concentrated in the placentae or fetal plasma when compared to maternal plasma. Simultaneous infusion of beta-guanidinopropionic acid with 14C-creatine reduced both movement and accumulation of creatine into the fetoplacental unit. It is concluded that the accumulation of creatine by the chorioallantoic placenta and by the visceral yolk sac is an active process with creatine diffusing down its concentration gradient into the fetal circulation.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D003401:Creatine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D005260:Female; D005865:Gestational Age; D006146:Guanidines / Q000494:pharmacology; D007263:Infusions, Parenteral; D008431:Maternal-Fetal Exchange; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011422:Propionates / Q000494:pharmacology; D051381:Rats; D014508:Urea / Q000097:blood / Q000378:metabolism; D015017:Yolk Sac / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D006146:Guanidines; D011422:Propionates; D014508:Urea; D003401:Creatine; C005775:guanidinopropionic acid