title: Permeability of peptides and proteins in human cultured alveolar A549 cell monolayer.
abstract: OBJECTIVE
  The transport of peptides or proteins across the alveolar cell monolayer was studied in vitro in order to elucidate their transport pathway.
  
  
  METHODS
  The permeability of 14 peptides or proteins and 6 dextrans with MW 1,000-150,000 was measured in cultured human lung adenocarcinoma A549 cell monolayers at 37 degrees C or 4 degrees C. The stability of the tested peptides and proteins was also evaluated.
  
  
  RESULTS
  The permeability coefficients of these macromolecules across the A549 cell monolayer at 37 degrees C ranged from 10(-5) to 10(-7) (cm/sec), and exhibited a good inverse correlation with molecular weight. All macromolecules were stable throughout the transport experiment, and degradation by proteases was minimal. Permeability at 4 degrees C did not differ from that at 37 degrees C. Clear selectivity for direction of transport was not observed.
  
  
  CONCLUSIONS
  These results suggested that the tested peptides and proteins appeared to penetrate the A549 cell monolayer via a paracellular route by passive diffusion.
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism; D001920:Bradykinin / Q000378:metabolism; D003911:Dextrans; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D010539:Permeability; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D003911:Dextrans; D010455:Peptides; D011506:Proteins; C015219:fluorescein isothiocyanate dextran; D016650:Fluorescein-5-isothiocyanate; D001920:Bradykinin