title: Mucosal in vitro permeability in the intestinal tract of the pig, the rat, and man: species- and region-related differences.
abstract: BACKGROUND
  The barrier properties of the gastrointestinal mucosa may be studied by measuring its permeability to different-sized marker molecules. Owing to difficulties in obtaining human tissue it is, however, often necessary to extrapolate findings from experimental animals to man. The aim of the present study was to compare regional intestinal mucosal permeability in man, the rat, and the pig, using the same marker molecules and in vitro technique.
  
  
  METHODS
  Segments from jejunum, ileum, colon, and rectum were mounted in Ussing diffusion chambers, and the mucosa-to-serosa passage of 14C-mannitol, fluorescein isothiocyanate (FITC)-dextran 4,400, alpha-lactalbumin, ovalbumin, and FITC-dextran 70,000 was studied.
  
  
  RESULTS
  Irrespective of species or intestinal region an inverse relationship between the molecular weight of the markers and the permeability was seen. The mannitol permeability was higher in the small intestine than in the colon in man, whereas the rat showed a higher permeability in the ileum than in the jejunum and colon. The FITC-dextran 4,400 permeability was higher in all intestinal regions in the rat than in man and the pig. The macromolecules showed low permeability with no regional differences.
  
  
  CONCLUSIONS
  The results showed differences between intestinal regions and between species. Permeability data from the pig correlated fairly well with those of man, whereas the rat differed, making it difficult to extrapolate from the rat to man.
authors.affiliation: Dept. of Animal Physiology and Surgery, Lund University, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Nejdfors
authors.forename: M
authors.initials: M
authors.lastname: Ekelund
authors.forename: B
authors.initials: B
authors.lastname: Jeppsson
authors.forename: B R
authors.initials: BR
authors.lastname: Weström
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015415:Biomarkers; D003911:Dextrans / Q000378:metabolism; D004195:Disease Models, Animal; D004594:Electrophysiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013552:Swine
chemical_list: D015415:Biomarkers; D003911:Dextrans