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.