a kinin, CHNO, released from blood plasma by some snake venoms and certain other enzymes, which slows intestinal contractions, lowers blood pressure, etc.
See bradykinin in American Heritage Dictionary 4
(brădˌĭ-kīˈnĭn, -kĭnˈĭn)
noun
A biologically active polypeptide, consisting of nine amino acids, that forms from a blood plasma globulin and mediates the inflammatory response, increases vasodilation, and causes contraction of smooth muscle.