Passage of molecules through the wall of the gastrointestinal tract. Influence of lysolecithin on rat ileal permeability to different-sized molecules.

We have studied the influence of lysolecithin on mucosal permeability to different-sized molecules in the distal part of the ileum. Using a rat experimental model, we determined the intestinal permeability to ethylene glycol (62 dalton), different-sized polyethylene glycols (634- to 1206-dalton PEGs), and dextran 3000, in the absence and presence of lysolecithin. We also examined the morphology of the ileal mucosa and determined the activity of brush border enzymes after deposition of lysolecithin in the gut lumen. We found that lysolecithin did not affect the absorption of ethylene glycol and had no influence on the activities of the enzymes. In contrast, lysolecithin enhanced the desquamation of enterocytes at the villous tips and increased the permeability to 634- to 1206-dalton PEGs and dextran 3000. These findings indicate that lysolecithin may facilitate the uptake of larger, potentially antigenic and toxic molecules in the distal ileum, although the underlying epithelial desquamation might have little or no influence on the absorption of small compounds.