The transfer of free fatty acids across the rabbit placenta.

Abstract

SUMMARY1. The passage of fatty acids across the placenta was studied in 28 day pregnant rabbits (i) by comparing the fatty acid distribution in plasma free fatty acids (FFA) of umbilical cord artery and vein with that in maternal plasma and (ii) by infusing the doe at a constant rate with labelled palmitic, linoleic or arachidonic acids. During the infusion maternal and foetal plasma FFA specific activities were measured.2. The mean levels of all the fatty acids studied (from twelve to twenty carbon atoms) were similar in both the umbilical vein plasma and maternal arterial plasma FFA, except for arachidonic acid, which was higher in foetal blood. The relative distribution of the fatty acids in umbilical arterial plasma was similar to that in the vein, but at lower concentrations. The mean cord venous-arterial difference for each fatty acid correlated positively with the mean maternal arterial levels, with the exception of arachidonic acid.3. During the constant infusion experiments the specific activities of the fatty acids in the maternal and foetal circulating FFA pools rose rapidly during the first 4 min then rose only slowly. Palmitic and linoleic acids were cleared from the maternal circulation in a similar manner and crossed the placenta at similar rates.4. The average foetal specific activity in plasma FFA reached 15 % of the maternal level for both palmitate and linoleate. The figure for arachidonic acid was half that for palmitic acid infused at the same time.5. It is concluded that (i) all the major fatty acids present in foetal adipose tissue cross the placenta, (ii) the net transport of each fatty acid depends in part on maternal concentrations, (iii) the rate of metabolism of palmitic and linoleic acids is the same and both cross the placenta at the same rate. Proportionately less foetal arachidonic acid is derived from maternal FFA, and (iv) the results suggest a second placental source of arachidonic acid and possibly also of other fatty acids.

Maternal Hypercholesterolemia Enhances Atherogenesis in Normocholesterolemic Rabbits, Which Is Inhibited by Antioxidant or Lipid-Lowering Intervention During Pregnancy

“…However, shifts in placental passage of specific FAs resulting from the hypocholesterolemic intervention may also have played a role. 30 Combinations of cholestyramine and vitamin E tended to be even more protective than cholestyramine or vitamin E alone, in particular in rabbits fed Chol 2, but failed to completely abolish the increase in lesion formation compared with normocholesterolemic controls, probably because of insufficient protection achieved under the present experimental conditions.…”

Changes in the Lipid Composition of the Internal Organs of Fetal Pigs From Sows Fed Different Dietary Fats

“…The transport of FFA across the placenta has been demonstrated in several species (Hershfield and Nemeth 1968;Portman etal.1969;Elphick et al 1975). Of necessity the essential fatty acids (linoleic acid l8.2 n-6, and linolenic acid 18:3 n-3) found in fetal tissue can only come from maternal sources (Hahn 1972 Elphick andHull 1977;Battaglia and Meschia 1978). In this study, sows received different amounts of 18:2 and 18:3 depending on their diet, but this did not appear to affect fetal tissue l82 n-6 and 1 8:3 n-3 levels.…”

Incorporation <i>in vivo</i> of 1-¹⁴C-Palmitic Acid into Placental and Fetal Liver Lipids of the Rabbit

“…NS = not significant. the placenta, the fetal blood loses up to 15% of its label, although at the same time being enriched with unlabelled fatty acid (Elphick et al, 1977). Thus the fetal and maternal circulat ing pools of FFA rapidly exchange with pools in the placenta.…”

“…All were studied at 28 days gestation (term = 31 days). The experimental proce dures have been described in detail elsewhere Elphick and Hull, 1977). Briefly, the experiments were performed as follows.…”