AJP - Cell Physiology, Vol 261, Issue 6 C1042-C1047, Copyright © 1991 by American Physiological Society
Pentose phosphate pathway in cellular trophoblasts from full-term human placentas
A. J. Moe, D. R. Farmer, D. M. Nelson and C. H. Smith
Edward Mallinckrodt Department of Pediatrics, Children's Hospital, St. Louis, Missouri.
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.
