The role of bestatin-sensitive aminopeptidase, angiotensin converting enzyme and thiorphan-sensitive "enkephalinase" in the potency of enkephalins in the guinea-pig ileum.
The role of each enkephalin-hydrolyzing peptidase in the inhibitory potency of exogenously added enkephalins in the myenteric plexus-longitudinal muscle preparation of guinea-pig ileum was studied by using the relatively specific inhibitor of each enzyme. Results showed that three distinct enzymes, bestatin-sensitive aminopeptidase(s), angiotensin converting enzyme, and thiorphan-sensitive "enkephalinase", played a critical role in the inactivation of enkephalins. Additionally, these enzymes are likely to be located close to opioid receptors, since they produce a significant concentration difference of enkephalin between the surrounding organ bath and the vicinity of opioid receptors. In contrast to these three enzymes, both L-tyrosyl-L-tyrosine-sensitive dipeptidyl aminopeptidase and D-phenylalanine-sensitive carboxypeptidase are indicated not to be involved significantly in the degradation of exogenously added enkephalins in the guinea-pig ileum.
D000603:Amino Acids, Sulfur / Q000494:pharmacology*; D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents; D002216:Captopril / Q000494:pharmacology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D004745:Enkephalins / Q000378:metabolism / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D015260:Neprilysin; D009842:Oligopeptides / Q000494:pharmacology; D010455:Peptides; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D015244:Thiorphan; D008625:Tiopronin / Q000031:analogs & derivatives / Q000494:pharmacology*
D000603:Amino Acids, Sulfur; D000900:Anti-Bacterial Agents; D004745:Enkephalins; D009842:Oligopeptides; D010455:Peptides; C016977:amastatin; D002216:Captopril; D015244:Thiorphan; D008625:Tiopronin; D010450:Endopeptidases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D007703:Peptidyl-Dipeptidase A; D015260:Neprilysin; D007930:Leucine; C012211:ubenimex