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Any of various structurally related polypeptides, such as bradykinin, that act locally to induce vasodilation and contraction of smooth muscle.
[Short for bradykinin.]
1. (Biochemistry) any of a group of polypeptides in the blood that cause dilation of the blood vessels and make smooth muscles contract
2. (Botany) another name for cytokinin
[C20: from Greek kin(ēma) motion + -in]
ki•nin(ˈkaɪ nɪn, ˈkɪn ɪn)
2. any of a group of hormones, formed in body tissues, that cause dilation of blood vessels.