Characterization of glucose transport in preimplantation mouse embryos

Gardner H.G. and Kaye P.L. (1995) Characterization of glucose transport in preimplantation mouse embryos. Reproduction, Fertility and Development, 7 1: 41-50. doi:10.1071/RD9950041


Author Gardner H.G.
Kaye P.L.
Title Characterization of glucose transport in preimplantation mouse embryos
Journal name Reproduction, Fertility and Development   Check publisher's open access policy
ISSN 1448-5990
Publication date 1995-01-01
Sub-type Article (original research)
DOI 10.1071/RD9950041
Open Access Status
Volume 7
Issue 1
Start page 41
End page 50
Total pages 10
Subject 1103 Clinical Sciences
1309 Developmental Biology
1311 Genetics
1305 Biotechnology
1312 Molecular Biology
1310 Endocrinology
2743 Reproductive Medicine
Abstract Membrane transport of glucose divorced from metabolism, was analysed in 2-cell embryos, morulae and blastocysts in the preimplantation mouse. A non-metabolizable radiolabelled analogue, 3,0 methyl D-glucose (30MG) was used, and glucose was used as well in morulae and blastocysts; incubation times were <5 min. Uptake occurred by combination of a non-saturable process, resistant to cytochalasin-B, and a facilitated process exhibiting classic Michaelis-Menten kinetics. The rate constant for the non-saturable component increased from l-22±0-12pL embryo-1 min-1 in 2-cell embryos to 2-08±0-44pL embryo-1 min-1 in blastocysts, determined using 30MG. The Km values of the saturable component for 30MG at 22°C were relatively constant at about 6-5 mM in 2-cell embryos, morulae and blastocysts. At 37°C, the Km increased from 6 mM in 2-cell embryos to 17 mM in blastocysts. Vmax increased about five-fold during development from the 2-cell stage to the morula stage and about three-fold during development to the blastocyst. The Km values for glucose in morulae and blastocysts were constant at about 1-3 mM at 37°C. Uptake of 30MG in blastocysts was inhibited by glucose and stimulated by incubation in glucose-free medium. There was no kinetic evidence for the participation of multiple saturable components in uptake by blastocysts or morulae. This supports the observation that the glucose transporter GLUT2, which is first expressed at the 8-cell stage to supplement GLUT1 expressed in the oocyte, does not contribute to the uptake of environmental glucose and is, therefore, probably restricted in expression to abcoelic membrane areas of the trophectoderm. Together with the known values of glucose in uterine fluid, the kinetic data indicate that most glucose enters the trophectoderm by this GLUT1 at a rate which directly reflects the external glucose concentrations. The activity increased on a cellular basis as development proceeded, suggesting increased activity to meet the increasing metabolic requirements of the blastocyst for glucose.
Keyword 2-cell embryo
Blastocyst
Kinetics
Methylglucose
Q-Index Code C1
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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