Tripeptide transport in rat lung

Biochim Biophys Acta. 1994 Mar 23;1190(2):430-4. doi: 10.1016/0005-2736(94)90104-x.


Transport of L-alanyl-D-phenylalanyl-L-alanine was investigated with an in situ vascular perfusion preparation of rat lung and brush border membrane vesicles prepared from type II pneumocytes. In the perfused lung 1 mM tripeptide was transported intact from the alveolar lumen to the vascular perfusate at a mean rate of 25.1 +/- 1.29 (3) nmol/min per g dry weight. D-Phenylalanine also appeared in the vascular perfusate at a rate of 21.9 +/- 1.74 (3) nmol/min per g dry weight indicating that 47% of the absorbed tripeptide was split during passage across the epithelial layer. No dipeptide could be detected in the vascular effluent during perfusions with tripeptide. Rapid L-alanyl-D-phenylalanyl-L-alanine uptake occurred with fresh apical membrane vesicles prepared from type II pneumocytes and this was abolished by treatment with 0.1% triton. The related tripeptide, D-alanyl-L-phenylalanyl-D-alanine, was taken up significantly more slowly by the vesicles. D-phenylalanyl-L-alanine and D-phenylalanyl-D-alanine, were also studied with the vascularly perfused preparation; the mixed dipeptide appeared in the vascular perfusate significantly faster than L-alanyl-D-phenylalanyl-L-alanine whereas D-phenylalanyl-D-alanine appeared more slowly and was not hydrolysed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Transport
  • Cell Membrane / metabolism
  • Epithelium / metabolism
  • Lung / metabolism*
  • Lung / ultrastructure
  • Male
  • Microvilli / metabolism
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / metabolism*
  • Phenylalanine / metabolism
  • Rats
  • Rats, Wistar


  • Peptides
  • Phenylalanine