Prostaglandin Biosynthesis in the Human Umbilical Cord

Abstract

The content of prostaglandins (PGs) in homogenates of arteries, connective tissue from human umbilical cords, and the capacity for biosynthesis of PGs in these tissues were studied. Lipid extracts were prepared and subjected to chromatography on silicic acid columns. PGs were eluted by ethyl acetate after elution with ethyl acetate benzene (1:9) and determined by bioassay. For studies of the content of PGs, the cords were immediately frozen after delivery and homogenized in cold ethanol. Cords taken at vaginal deliveries contained amounts equivalent to approximately 700 ng prostaglandin E₂/g dry weight and cords taken at caesarean sections about 450 ng/g. After homogenization and incubation of arteries in potassium phosphate buffer at 37 °C for 30 min the PG content increased from about 80 to 200 ng/g. Addition of arachidonic acid increased the biosynthesis fivefold. Indomethacin inhibited it. Most of the smooth muscle stimulating activity of the homogenated cords was due to prostaglandin E compounds, but smooth muscle stimulating material similar to prostaglandin F_1α and F_2α was also present. Prostaglandin E₂ was conclusively identified by gas chromatography – mass spectrometry. The findings are compatible with the view that local biosynthesis of PGs is very active in the human umbilical cord after delivery.