Hexose transport in preimplantation rabbit blastocysts.

Transtrophectodermal 3-0-methyl glucose (3-0MG) transport in the rabbit blastocyst at Days 6 and 7 post coitum was investigated to understand better how the trophectoderm can regulate inner cell mass growth by controlling substrate availability. 3-0MG rapidly traversed the trophectoderm and displayed saturation kinetics (Km = 4.3 +/- 0.5 mM, Vmax = 79 +/- 3.8 nmol.cm-2). The flux of 3-0MG was inhibited nearly 95% by 10(-4) M-phloretin, and only 15% by 10(-4) M-phlorizin. Furthermore, 3-0MG influx was inhibited by cytochalasin B (5 microM) and was unaffected by removal of sodium. The transport system had a high specificity for 2-deoxy-D-glucose and glucose, and a very low specificity for fructose and 4-alpha-methyl glucoside. Western blots probed with a polyclonal antibody to the human erythrocyte glucose transport protein and also with a polyclonal antibody to the C-terminus of the glucose transport protein of the rat brain revealed a broad band with a molecular weight of 55,000. Using immuno-gold labelling techniques, Na(+)-independent glucose transporters were localized to both the apical and basolateral borders of the trophectodermal cell. These results suggest that the mechanism in the trophectoderm responsible for transport of glucose is similar to other sodium-independent glucose transport systems. In addition, 3-0MG influx was unaffected by short-term incubation with progesterone, the progesterone antagonist mifepristone (RU-486), PGF-2 alpha, PGE-2, insulin, or cAMP. Day-7 p.c. embryos also transported hexoses by a similar system because the influx rate and the phlorizin/phloretin sensitivity were the same as in the Day-6 p.c. embryo.

[1]  D. H. Robinson,et al.  Macromolecular transport in rabbit blastocysts: evidence for a specific uteroglobin transport system , 1989, Molecular and Cellular Endocrinology.

[2]  H. Leese,et al.  The role of glucose and pyruvate transport in regulating nutrient utilization by preimplantation mouse embryos. , 1988, Development.

[3]  J. Zigler,et al.  Identification of the monkey lens glucose transporter by photoaffinity labelling with cytochalasin B. , 1988, Investigative ophthalmology & visual science.

[4]  M. Rosenfeld,et al.  Characterization of antisera to a synthetic carboxyl-terminal peptide of the glucose transporter protein. , 1988, Journal of Biological Chemistry.

[5]  J. Slot,et al.  Insulin-induced translocation of glucose transporters from post-Golgi compartments to the plasma membrane of 3T3-L1 adipocytes , 1988, The Journal of cell biology.

[6]  D. Benos,et al.  Mineralocorticoid concentrations in unstressed female rabbits and embryonic sodium transport. , 1987, Journal of reproduction and fertility.

[7]  S. Shenolikar,et al.  Evidence that forskolin binds to the glucose transporter of human erythrocytes. , 1987, The Journal of biological chemistry.

[8]  R. Wales,et al.  Effects of prostaglandins E-2 and F-2 alpha on the metabolism of [U-14C]glucose by mouse morulae-early blastocysts in vitro. , 1987, Journal of reproduction and fertility.

[9]  B. Kahn,et al.  Cell Biology of Insulin's Stimulatory Action on Glucose Transport and Its Perturbation in Altered Metabolic States , 1986, Annals of the New York Academy of Sciences.

[10]  H. Joost,et al.  Insulin-stimulated glucose transport in rat adipose cells. Modulation of transporter intrinsic activity by isoproterenol and adenosine. , 1986, The Journal of biological chemistry.

[11]  I. Rosenblum,et al.  Stage-specific insulin binding in mouse preimplantation embryos. , 1986, Developmental biology.

[12]  H. D. Kim,et al.  Inhibition of 3-O-methylglucose transport in human erythrocytes by forskolin. , 1985, The Journal of biological chemistry.

[13]  G. Lienhard,et al.  Endoglycosidase f cleaves the oligosaccharides from the glucose transporter of the human erythrocyte. , 1984, Biochimica et biophysica acta.

[14]  G. Esposito Intestinal Permeability of Water-Soluble Nonelectrolytes: Sugars, Amino Acids, Peptides , 1984 .

[15]  W. Rees,et al.  The Insulin-Sensitive Hexose Transport System in Adipocytes , 1983 .

[16]  D. Dabich,et al.  Transport of glucosamine (aldohexoses) by preimplantation mouse blastocysts. , 1982, Biochimica et biophysica acta.

[17]  D. Benos Developmental changes in epithelial transport characteristics of preimplantation rabbit blastocysts. , 1981, The Journal of physiology.

[18]  K. Ullrich Sugar, amino acid, and Na+ cotransport in the proximal tubule. , 1979, Annual review of physiology.

[19]  A. Enders,et al.  Junctional complexes in the preimplantation rabbit embryo , 1975, The Anatomical record.

[20]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.

[21]  J. C. Daniel Early Growth of Rabbit Trophoblast , 1964, The American Naturalist.

[22]  C. Lutwak-Mann Glucose, Lactic Acid and Bicarbonate in Rabbit Blastocyst Fluid , 1962, Nature.

[23]  L. Fridhandler Pathways of glucose metabolism in fertilized rabbit ova at various pre-implantation stages. , 1961, Experimental cell research.

[24]  C. Lutwak-Mann,et al.  Some Properties of the Rabbit Blastocyst , 1954 .