TEST CONDITIONS GREATLY INFLUENCE PERMEATION OF WATER-SOLUBLE MOLECULES THROUGH THE INTESTINAL-MUCOSA - NEED FOR STANDARDIZATION

Permeability tests are widely used to investigate the pathogenesis of various gastrointestinal diseases including coeliac disease, infectiou s diarrhoea, and inflammatory bowel disease. In Crohn's disease they a re used as activity parameters by some investigators. Lack of standard isation, however, makes it very difficult to compare data reported in different studies. The aim of this study was to gather permeation data in well controlled test conditions to standardise the methods. Nine h ealthy volunteers each received five consecutive permeability tests by mouth using polyethylene glycol-400 (PEG-400) and Cr-51-EDTA as probe molecules. The probes were dissolved in water, a glucose solution, a starch solution, a hyperosmolar lactulose-mannitol solution, and a Liq uid meal. A significantly decreased permeation for both probes was fou nd when given with the hyperosmolar solution. The Cr-51-EDTA permeatio n was also decreased with water. The permeability index, Cr-51-EDTA/PE G-400, corrected for influencing factors, confirmed that the lactulose -mannitol solution and plain water yield lower values of macromolecule permeation than starch, glucose or liquid meal. Hyperosmolarity was d early accompanied by a decrease in permeability probably caused by rev ersed solvent drag. Interindividual variability of probe permeation an d permeability index is very low with a standard Liquid meal. It is pr oposed that for permeability studies a standard liquid meal is always used.