Transport of glucosamine (aldohexoses) by preimplantation mouse blastocysts

A carrier-mediated system for uptake of glucosamine (and other aldohexoses) was identified in preimplantation mouse blastocysts. With early and late blastocysts, the values for Km (525 +/- 82 and 651 +/- 137 microM, respectively) and V (0.29 +/- 0.02 and 0.29 +/- 0.04 pmol/h per ng protein, respectively) for glucosamine are statistically indistinguishable. The same carrier system, therefore, is operative at the two developmental stages. Glucosamine uptake was temperature sensitive and inhibited by structural analogues and phloretin.