Kininase Activity of Human Saliva

Abstract

DURING investigations on a substrate-plasma for plasmakinin-forming enzymes¹, human saliva was used as one source of such enzymes. It has previously been well established that human saliva contains plasma-kinin-forming enzymes². We found that, when 0.2 ml. saliva was added to 1 ml. substrate-plasma which was free from kininase activity, considerable amounts of plasma-kinin were formed; but it was eventually broken down. This finding seemed to indicate that human saliva contained kininase activity. To investigate if that was really the case, synthetic bradykinin (Sandoz, Ltd.) 500 ng/ml. was added to the saliva and the mixture repeatedly tested for bradykinin activity on a rat uterus suspended in aerogen-ated de Jalons solution. The bradykinin activity disappeared rapidly from the mixture (Fig. 1). The kininase activity was not equally intense in all salivas tested.