Identification of kallidin degrading enzymes in the isolated perfused rat heart

Kallidin (KD) is an important vasoactive kinin whose physiological effects are strongly dependent on its degradation through local kininases. In the p resent study, we examined the spectrum of these enzymes and their contribut ion to KD degradation in isolated perfused rat hearts. By inhibiting angiot ensin-converting enzyme (ACE), aminopeptidase M (APM) and neutral endopepti dase (NEP) with ramiprilat (0.25 mu M), amastatin (40 mu M) and phosphorami don (1 mu M), respectively, relative kininase activities were obtained. APM (44%) and ACE (35%) are the main KD degrading enzymes in rat heart; NEP (7 %) plays a minor role. A participation of carboxypeptidase N (CPN) could no t be found.