Utero-placental transfer of octanoic, palmitic and linoleic acids during late gestation in gilts.

The transfer across the swine uterus and placenta of [1-14C]octanoic acid, [9,10(n)-3H]palmitic acid and [1-14C]linoleic acid was studied in five gilts and their fetuses during late gestation following a single bolus injection. Only trace amounts of labeled fatty acids were found in fetal plasma lipid. The highest fetal plasma lipid values were less than 1.2% of the peak maternal values. The concentration of plasma free fatty acids (FFA) and fatty acid profiles in the umbilical artery (FA) and vein (FV) and uterine artery (UA) and vein (UV) were compared. There were no measurable umbilical arterio-venous differences. Concentrations of FFA in FA and FV were about 40% of the UA and UV values (187, 194, 73, 82 microEq/liter for UA, UV, FA and FV, respectively). Fetal plasma contained larger amounts of 14:0, 16:1, 18:1 and 20:4, whereas maternal plasma contained larger amounts of 18:0 and 18:2. There was difference between fetal and maternal plasma for 16:0 and 18:3; the latter was present only in minute amounts. In conclusion, only trace amounts of FFA cross the swine placental tissues during late gestation; therefore, their contribution to fetal energy supply or lipid storage appears limited.