Specificity: Substance P occurs in nerve fibers of the central and peripheral nervous system and in endocrine cells of the gut. Substance P containing nerve fibers in the gut wall are particularly numerous in the myenteric plexus and the smooth muscle layers. Substance P containing tumors arising in the ileum are often associated with the "carcinoid syndrome", characterized by flushing of the skin, diarrhea, bronchoconstriction and sudden drops in blood pressure. Substance P is commonly found in midgut carcinoids and some of the symptoms may be related to this peptide. This antibody is reactive in human and rat. Immunogen: Synthetic Substance P coupled to KLH.