Kinins produced from bovine colostrum by kallikrein and saliva.

Substances capable of stimulating smooth muscle are produced on the incubation of bovine colostrum with urinary kallikrein or calf saliva. These substances, called urine- and saliva-colostrokinin, have been differentiated from kallidin, substance A and similar smooth muscle activating agents. Saliva-colostrokinin is likely to be formed in the suckling calf. Further, as colostrum became milk, the ability to form colostrokinin diminished. A function for saliva-colostrokinin in the newborn is suggested.