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 (triiodothyronine) 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 labelled compound administration. The hormone effect was similar in phosphatidylcholine and lysophosphatidylcholine. The preliminary hormone effect was maximum 5.5 h after T3 injection. The levels of methylated precursors were studied by radioactivity and lipid P determinations; these levels were constant throughout the timecourse experiment. It was concluded that the increase in methyl group incorporation is due to a hormone-dependent increase in phospholipid turnover. (author)