Pentose phosphate pathway in cellular trophoblasts from full-term human placentas.
Glucose metabolism was investigated in cellular trophoblasts isolated from full-term human placentas. The specific yields of 14CO2 from D-[1-14C]glucose and D-[6-14C]glucose were used to determine glucose metabolism via the pentose cycle for cells freshly isolated or cells grown in culture for 1 and 3 days. Cells were mononucleated on day 1 but fused to form multinucleated syncytiotrophoblasts by day 3. The principal product of glucose metabolism under all conditions was lactate, accounting for approximately three-fourths of recovered 14C in products. Pentose cycle activity contributed 0.57 +/- 0.01, 0.39 +/- 0.06, and 0.21 +/- 0.05% of the glucose metabolized by cells freshly isolated, cultured for 1 day, and cultured for 3 days, respectively. In the presence of the electron acceptor methylene blue, pentose cycle activity increased to 16.5 +/- 2.1, 13.8 +/- 1.5, and 18.2 +/- 1.7% for cells freshly isolated, cultured for 1 day, and cultured for 3 days, respectively. Trace amounts of 14C were recovered in other products including amino acids and glycogen. These data suggest that pentose cycle activity in cellular trophoblasts from full-term placenta, like those in full-term villous tissue, is a minor component of glucose metabolism. However, these cultured cells maintain a capacity to oxidize glucose via the pentose cycle at relatively high rates.
Moe
A J
AJ
Edward Mallinckrodt Department of Pediatrics, Children's Hospital, St. Louis, Missouri.
Farmer
D R
DR
Nelson
D M
DM
Smith
C H
CH
D002250:Carbon Radioisotopes; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010427:Pentose Phosphate Pathway; D010920:Placenta / Q000166:cytology / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism*
D002250:Carbon Radioisotopes; D005947:Glucose