Origin of biliary phosphatidylcholines studied by coenzyme labelling with [1,1-2H2]ethanol.

The labelling of individual molecular species of phosphatidylcholines in bile and liver was measured in bile fistula rats given [1,1-2H2]ethanol immediately after the cannulation of the bile duct. Corresponding species in liver and bile were labelled to the same extent, the deuterium excess in the glycerol moiety (at C-2) of biliary molecules with rapid turnover possibly being slightly higher in the bile than in liver. The labelling of different positions and the half-life times of different molecular species were about the same as previously found 48 h after the cannulation. The only exception was the 1-stearoyl-2-linoleoyl species, which had a half-life time 5-7 times longer immediately after operation than after 48 h of biliary drainage. The results support our previous conclusion that the molecular species of phosphatidylcholines in liver and bile represent the same, or very similar, pool(s) of molecules.