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Any member of a group of polypeptides, widely scattered in vertebrate and invertebrate tissues, which have in common four of the five terminal amino acids: Phe-Xaa-Gly-Leu-Met-NH2; pharmacologically, they all cause hypotension in mammals, contraction of gut and bladder smooth muscle, and secretion of saliva.
[G. tachys, swift, + kineō, to move, + -in]
tachykinin/tachy·ki·nin/ (-ki´nin) any of a family of peptides structurally and functionally similar to substance P; all are potent, rapidly acting secretagogues and cause smooth muscle contraction and vasodilation.
See substance P.
tachykinin(tăk″kī′nĭn) [″ + ″],
Any of a large family of peptides that function as neurotransmitters in the central and peripheral nervous systems. They have extraneuronal activity in other body tissues. Their diverse biological actions are mediated through cellular G proteins.