Effect of a single dose of T3 on the incorporation of (Methyl-14C) methionine into phosphatidylcholine and lysophosphatidylcholine in chick liver.

The preliminary effect of a single dose of T3 (Triidothyronine) on the incorporation of (Methyl-14C) Methionine into liver phosphatidylcholine, lysophosphatidylcholine and methylated precursors was studied in chick liver from 0.25 to 6 hours. Chicks received a T3 dose intraperitoneally 5 h prior labeled compound administration. It can be deduced that the hormone effect is similar in phosphatidylcholine and lysophosphatidylcholine. In our conditions, the preliminary hormone effect is maximum 5 1/2 h after T3 injection. The levels of methylated precursors have been studied by radioactivity and lipid P determinations; these levels are constant throughout the time course experiment. We conclude that the increase in methyl group incorporation is due to a hormone-dependent increase in phospholipid turnover.