Kallikrein-Induced Rat Uterus Contraction is Dependent on Kinin Release

Glandular kallikrein (EC.3.4.21.8) releases lisyl-bradykinin (kallidin) from kininogen substrates by limited proteolysis (Chao et al, 1981). The responses of the smooth muscle to kallikrein are attributed to kinin formation and a subsequent peptide-receptor interaction (Barabe et al,1977; Fritz et al, 1979; Odya and Goodfriend, 1979). Beraldo et al.(1966) reported that rat urinary kallikrein induced rat uterine contractions in the absence of added kininogen. Nustad and Pierce (1974) suggested that uterine contractions elicited by rat urinary kallikrein depend on kinin liberation from some uterine kininogen. Beraldo et al.(1976) demonstrated the presence of kininogen in the rat uterus. Chao et al.(1981) reported that rat glandular kallikrein can cause the contraction of isolated rat uterus independent on kinin formation. As can be seen, the mechanism of kallikrein-induced uterine contraction was uncertain. We used pure rat submandibular gland kallikrein in order to explain this mechanism.