Glycine and Na+ transport in preimplantation mouse embryos.
The dependence of glycine uptake on glycine and Na+ concentrations was determined and compared in 2-cell embryos and blastocysts. In both, uptake was by a combination of a Na+-independent non-saturable route and a Na+-dependent saturable system with Km values of 62 microM and 274 microM for 2-cell embryos and blastocysts respectively. Na+-dependent saturable uptake by embryos of both stages had a Hill coefficient of 2 for Na+, indicating co-transport of 2 Na+ with each glycine molecule. These results suggest that glycine enters 2-cell embryos by the gly-system, and blastocysts by a similarly Na+-dependent system with characteristics resembling the A-system.
D000818:Animals; D001692:Biological Transport; D001755:Blastocyst / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D051379:Mice; D012964:Sodium / Q000378:metabolism*
D012964:Sodium; D005998:Glycine