Abstract
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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
