Increase in human placental glucose transporter-1 during pregnancy.

Glucose transporter-1 (GLUT1) has been found in high abundance in human placentas. The purpose of this study was to analyze the changes in the level of GLUT1 during pregnancy. We have analyzed the gestational changes in human placental GLUT1 by [3H]cytochalasin B binding assay, immunoblot analysis and Northern blot analysis. Levels of [3H]cytochalasin B binding to placental membrane in pregnancy at 7-10, 18-20 and 38-40 weeks were 4.2 +/- 0.47, 5.2 +/- 0.46 and 7.2 +/- 0.40 (mean +/- SEM, N = 4) mumol/kg protein, respectively. Amounts of 49-kD and 60-kD proteins detected in immunoblot analysis increased during pregnancy in parallel with [3H]cytochalasin B binding to placental membrane. The GLUT1 mRNA levels also increased during pregnancy. Immunohistochemical examination showed that GLUT1 was localized in the plasma membranes of trophoblast cells. These findings showed that the GLUT1 level increased during pregnancy in human placentas and suggest that GLUT1 may play an important role in fetal development.