Regulation of placental nutrient transport and implications for fetal growth

• Published in: Nutrition research reviews Vol. 15; no. 2; pp. 211 - 230
• Main Authors: Bell, Alan W, Ehrhardt, Richard A
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-12-2002
• Subjects: Amino acids; Biological and medical sciences; Embryology: invertebrates and vertebrates. Teratology; fetal development; fetal growth regulation; Fetal membranes; Fundamental and applied biological sciences. Psychology; General aspects. Development. Fetal membranes; Glucose; growth and development; maternal nutrition; maternal-fetal transfer; nutrient partitioning; Nutrient requirements; Nutrient transport; placenta; Fetal growth; Placental transport; Amino acids; Glucose; Regulatory factors; Human; Fetal membrane; Growth; Placental transfer; Biological transport; Review; Fetomaternal relation; Fetal development; Regulation(control); Placenta; Aminoacid; Nutrient; Macronutrient
• ISSN: 0954-4224; 1475-2700
• DOI: 10.1079/NRR200239

Fetal macronutrient requirements for oxidative metabolism and growth are met by placental transport of glucose, amino acids, and, to a lesser extent that varies with species, fatty acids. It is becoming possible to relate the maternal–fetal transport kinetics of these molecules in vivo to the expression and distribution of specific transporters among placental cell types and subcellular membrane fractions. This is most true for glucose transport, although apparent inconsistencies among data on the roles and relative importance of the predominant placenta glucose transporters, GLUT-1 and GLUT-3, remain to be resolved. The quantity of macronutrients transferred to the fetus from the maternal bloodstream is greatly influenced by placental metabolism, which results in net consumption of large amounts of glucose and, to a lesser extent, amino acids. The pattern of fetal nutrient supply is also altered considerably by placental conversion of glucose to lactate and, in some species, fructose, and extensive transamination of amino acids. Placental capacity for transport of glucose and amino acids increases with fetal demand as gestation advances through expansion of the exchange surface area and increased expression of specific transport molecules. In late pregnancy, transport capacity is closely related to placental size and can be modified by maternal nutrition. Preliminary evidence suggests that placental expression and function of specific transport proteins are influenced by extracellular concentrations of nutrients and endocrine factors, but, in general, the humoral regulation of placental capacity for nutrient transport is poorly understood. Consequences of normal and abnormal development of placental transport functions for fetal growth, especially during late gestation, and, possibly, for fetal programming of postnatal disorders, are discussed.