The role of glucose and pyruvate transport in regulating nutrient utilization by preimplantation mouse embryos

Abstract

Preimplantation mouse embryos utilize pyruvate preferentially during the early cleavage stages before switching to glucose at around the time of compaction. This switch in substrate preference has been studied using a non-invasive ultramicrofluorometric analytical technique on single mouse embryos. On the basis of transport kinetic studies and inhibition by phloretin, cytochalasin B and sugar analogues, a component of glucose uptake by mouse blastocysts was found to be mediated by facilitated diffusion. The J(max) and K(t) of this facilitated component were 3.53 pmol embryo-1h-1 and 0.14 mM, respectively. At physiological concentrations of glucose, the facilitated component accounts for arou..