Distribution of brush-border membrane peptidases along the intestine of rabbits and rats: implication for site-specific delivery of peptide drugs.

Distribution patterns of brush-border membrane dipeptidylpeptidase IV (DPP IV), endopeptidase-24.11, and angiotensin converting enzyme (ACE) activities along the intestine of the rat and rabbit were examined. ACE and endopeptidase-24.11 had a similar distribution profile in the intestine of the rat and rabbit, jejunum > duodenum approximately jejunoileal junction > ileum > caecum (rat) or ileocaecal junction (rabbit). DPP IV had a more uniform distribution pattern than ACE and endopeptidase-24.11. Its longitudinal distribution patterns in the intestine of the rat and rabbit were slightly different. In the rat intestine, DPP IV activity had the following rank order: ileum approximately jejunum > jejunoileal junction > duodenum > caecum. In the rabbit, DPP IV had similar activities from the jejunum to the ileocaecal junction whereas its duodenal activity was much lower. The results suggest that the distribution profiles of DPP IV, ACE, and endopeptidase-24.11 are similar in both species.