Distribution of Label in Maternal Plasma, Placenta, Fetal Plasma and Tissues after Injection of ¹⁴C-Palmitate into the Circulation of 21- and 28-Day-Pregnant Rabbits

Abstract

Tissue and plasma samples were obtained from fetuses removed 1–20 min after injection of ¹⁴C-palmitate into the doe at day 21 or day 28 of gestation. Specific activity of maternal plasma free fatty acids (FFA) was higher, but that of fetal plasma FFA lower in 21- than 28-day-pregnant rabbits. In 21-day fetuses, total radioactivity in the liver never exceeded that in the placenta; in 28-day fetuses, the liver radioactivity exceeded that in the placenta after 3 min. Total radioactivity in the fetal brown adipose tissue (BAT) never exceeded that in the placenta. Most of the placental radioactivity was initially in the FFA, but at later time intervals the majority of the label was in the phospholipids. The fetal liver and BAT rapidly esterified label into triglycerides. It is concluded that transport of FFA across the placenta is greater at 28 days than at 21 days gestation. The evidence suggests that a pool of placental FFA, which equilibrates rapidly with the maternal plasma FFA, is a possible source of fetal plasma FFA. The rapidity and quantity of label appearing in the fetal liver suggest that fatty acids may first be processed by the liver before transport to extrahepatic tissues.

Utero-Placental Transfer of Octanoic, Palmitic and Linoleic Acids during Late Gestation in Gilts

“…Plasma FFA can cross the placenta from mother to fetus in a number of animals, including rats (Hummel et al, 1975;Pascaud et al, 1977), guinea-pigs (Hershfleld andNemeth, 1969), rabbits (Van Duyne et al, 1962;Elphick et al, 1978Elphick et al, , 1979Hudson et al, 1977) and monkeys (Portman et al, 1969). There also is evidence that the human placenta is permeable to FFA (Rubaltelli et al, 1978;Hull and Elphick, 1979).…”

The Labeling of Lung Phosphatidylchohne in Premature Rabbits

“…Elphick et al (1 1) demonstrated at 28 days gestational age, labeled palmitic acid administered to pregnant does appeared maximally in the fetal circulation within 3 min and had a half-life in the fetal circulation of 30-60 sec. The labeled fatty acids preferentially were incorporated into fetal phospholipids (15). Biezenski (5) has shown that esterified fatty acids and phospholipids do not cross HOURS Fig.…”

Transfert materno-fœtal et captation des acides gras essentiels chez le rat

“…Alors que la circulation et la captation par le foetus de mammifère des acides gras non essentiels tels que l'acide palmitique ont fait l'objet de recherches nombreuses (Hummel et al, 1974(Hummel et al, , 1975 Hudson et al, 1977) les recherches concernant les acides gras essentiels sont encore rares (Pascaud et al) …”