The enhancing effects of amastatin, phosphoramidon and captopril on the potency of [Met5]-enkephalin in rat vas deferens.

ABSTRACT

The enkephalin-inactivating enzymes in rat vas deferens were studied by using the relatively specific inhibitor of each enzyme. The results showed that the rat vas deferens, like the other three preparations, guinea-pig ileum, mouse vas deferens and striatal membranes of guinea-pig brain, which had been investigated previously, contained three distinct enkephalin-hydrolyzing peptidases. Additionally, the enkephalin-hydrolyzing aminopeptidase, endopeptidase-24.11 and peptidyl dipeptidase A in rat vas deferens were found to be inhibited maximally with 1 microM of amastatin, 1 microM of phosphoramidon and 1 microM of captopril, respectively. In contrast to these three enzymes, both L-tyrosyl-L-tyrosine-sensitive dipeptidyl aminopeptidase and D-phenylalanine-sensitive carboxypeptidase were suggested not to be involved significantly in the inactivation of exogenously given enkephalin in rat vas deferens. The characteristics of the enkephalin-degradative enzymes in rat vas deferens were discussed in terms of their similarities to and differences from those in the other preparations.