In vitro incorporation of acetate-1-14C into the phospholipids of rabbit and human endometria

Endometria from nonpregnant and 6-day pregnant rabbits and from humans in the proliferative and secretory phases were incubated with 1-¹⁴C-acetate.¹⁴CO₂ was collected, and subsequently the amounts, specific radioactivities, and in some cases the fatty acid compositions of the isolated phospholipids were determined. Phosphatidyl choline was the phospholipid present in highest amount in endometria from both nonpregnant and pregnant rabbits, and in human endometria; this phospholipid also showed the highest degree of incorporation of¹⁴C-acetate. Pregnancy in the rabbit seemed to decrease the incorporation of¹⁴C-acetate into most of the endometrial phospholipid classes. In humans, the incorporation of acetate into phosphatidyl choline and phosphatidyl ethanolamine was lower in the secretory than the proliferative endometria. Of the fatty acids, linoleic acid in phosphatidyl choline and phosphatidyl ethanolamine of the rabbit endometria showed a significant relative increase during pregnancy and palmitoleic acid showed a decrease. This investigation was supported by a grant from the Ford Foundation.