DIFFERENTIAL DISTRIBUTION AND METABOLISM OF ARACHIDONIC-ACID AND DOCOSAHEXAENOIC ACID BY HUMAN PLACENTAL CHORIOCARCINOMA (BEWO) CELLS

The time course of incorporation of [C-14]arachidonic acid and [H-3]do cosahexaenoic acid into various lipid fractions in placental choriocar cinoma (BeWo) cells was investigated. BeWo cells were found to rapidly incorporate exogenous [C-14]arachidonic acid and [H-3] docosahexaenoi c acid into the total cellular lipid pool. The extent of docosahexaeno ic acid esterification was more rapid than for arachidonic acid, altho ugh this difference abated with time to leave only a small percentage of the fatty acids in their unesterified form. Furthermore, uptake was found to be saturable. In the cellular lipids these fatty acids were mainly esterified into the phospholipid (PL) and the triacyglycerol (T AG) fractions. Smaller amounts were also detected in the diacylglycero l and cholesterol ester fractions. Almost 60% of the total amount of [ H-3]Docosahexaenoic acid taken up by the cells was esterified into TAG whereas 37% was in PL fractions. For arachidonic acid the reverse was true, 60% of the total uptake was incorporated into PL fractions wher eas less than 35% was in TAG. Marked differences were also found in th e distribution of the fatty acids into individual phospholipid classes . The higher incorporation of docosahexaenoic acid and arachidonic aci d was found in PC and PE, respectively. The greater cellular uptake of docosahexaenoic acid and its preferential incorporation in TAG sugges ts that both uptake and transport modes of this fatty acid by the plac enta to fetus is different from that of arachidonic acid.