AJP - Endocrinology and Metabolism, Vol 240, Issue 1 65-E71, Copyright © 1981 by American Physiological Society
Fatty acid metabolism in human fetal placental vasculature
T. N. Tulenko and J. L. Rabinowitz
The utilization of exogenous acetate and palmitate for the synthesis of
vascular wall lipids was studied in isolated blood vessels of the human
placenta under high- and low-oxygen conditions. Arteries and veins were
obtained from fresh placental material and incubated in Krebs-Henseleit
buffer (pH 7.4 at 37 degrees C) containing (in mM) either [2-14C]acetate,
0.11; [1-14C]palmitate, 0.43; or [16-14C]palmitate, 0.43. At the end of the
180-min incubation, neutral lipids accounted for 40%, and phospholipids
60%, of the 14C recovered. Following incubation with either precursor, 14C
label was recovered mainly in 16-carbon fatty acids (FA) (35%) and
18-carbon FA (45%); less than 10% was recovered in less than or equal to
14-carbon FA and greater than or equal to 20-carbon FA. Estimates of
synthesis rate however indicated that the 18- and 20-carbon FA had the
highest turnover rates. Schmidt degradation analysis demonstrated
considerable labeling of alkyl carbons after incubation with either
carboxyl- or alkyl-labeled precursors, indicating that FA degradation
products were used for de novo FA synthesis. Collectively, these findings
suggest the presence of both de novo and chain elongation pathways. No
differences were observed between arteries and veins, and anoxia had little
influence on FA metabolism. Analysis of ATP levels demonstrated elevated
concentrations of ATP present, accounting for the apparent lack of anoxic
inhibition of FA metabolism.
