Passage of molecules through the wall of the gastrointestinal tract. Increased passive permeability in rat ileum after exposure to lysolecithin.

The interaction between lysolecithin and mucosal cells in the distal ileum has been studied. Using a rat experimental model, we determined the intestinal permeability to fluorescent dextran 3000 after exposure to different amounts of lysolecithin. At pH 7.3, lysolecithin, 10 mg/ml, significantly enhanced the transmural passage, and at pH 3.5, even 1 mg/ml markedly increased the permeability. However, when lysolecithin was incubated with homogenized mucosal cells, a rapid disappearance of the compound occurred; this was accompanied by formation of free fatty acids and minor formation of lecithin. It appears, therefore, that high concentrations of lysolecithin can impair the intestinal barrier function in the distal part of ileum but that the mucosal cells are well equipped with activities for the rapid removal of such high concentrations. This could be physiologically significant, since the mucosal cells could otherwise be faced with large amounts of lysolecithin that might facilitate the absorption of potentially antigenic and toxic compounds.