PEDRO ROSSO Institute of Human Nutrition and Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New Yorfc, New Yorfc 10032 ABSTRACT Maternal-fetal transfer of glucose and methyl a-o-glucopyranoside (AMG) was studied in rats fed either a 6% or a 27% casein diet. On day 21 of pregnancy 3H-labeled glucose and 14C labeled AMG were injected into the maternal circulation of both groups of dams and concentration of tritium and 14C in maternal plasma, placentas and fetuses were determined 10 and 20 minutes later respectively. In malnourished rats both substances tended to be slightly, although non-significantly, increased in maternal plasma and were significantly decreased in placentas and fetuses. This lower concentration in fetal tissues reflected a marked reduc tion in the amount of glucose and AMG transported into the fetuses per g of placental tissue per minute. The proportionality of the changes found for both substances suggests that their reduced rate of transfer may be due to similar mechanisms. J. Nutr. 107: 2006-2010, 1977. INDEXING KEY WORDS maternal nutrition •placental transport The rate of transfer of a-amino isobutyric acid (AIE) a non metabolizable amino acid, from the maternal circulation into the fetus was found to be lower near term in protein restricted rats compared with controls (1). These results were interpreted as an indication that when nutrients are in short supply, the dam reduces the quantity of amino acids transferred into the fetus. The reduced transfer of nutrients would, in turn, prevent depletion of the maternal stores by the fetus. Such a phenomenon would explain why the dam seems to be propertionally less affected than the fetus after nutrient deprivation during pregnancy. In order to determine whether the reduced maternal-fetal transfer of AIB into the conceptus found in protein deprived animals reflects a general reduction in the transfer of nutrients Or it is specific to AIB maternal fpral nf crini-vico ana onrl /VID, maternai retai rransfpr transter or glucose or metnyl-a-D-gluCOPVranoside (AMG) a

non-metabolizable

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studied in rats fed a low casein and a control diet. Results of such a study are reported here, METHODS Sprague-Dawley rats (Holtzman strain) were shipped to our laboratory on the third day of pregnancy. This date was determined by the presence of spermatozoa in vaginal smears after overnight mating. Day after mating was counted as Day 0 of pregnancy. Dams were put in individual cages in a room with constant temperature and a 12 hour dark-light cycle. For one day they were fed a stock diet ad libitum and on the morning of the fifth day divided into an experimental and a control group fed a 6% Received for publication March 18, 1976. work was partially supported Grant 478'This of tnc Nutrltion Foundation. The by author is No. redptoat of a Research Career Development Award

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