Subtance P is responsible for a number of excitatory effects on both central and peripheral neurons. Substance P contracts smooth muscle, constricts bronchioles and increases capillary permeability. When released from afferent nerves, Substance P causes a neurogenic inflammatory response, including mast cell degranulation. NK-1 agonist; potent vasodilator and hypotensive agent; induces salivation; putative neurotransmitter in sensory (pain) afferents. Substance P(1-9) is a fragment of Subtance P. Accumulating evidence shows that N- and C-terminal substance P fragments have significant biological activity. Substance P(1-9) has been reported to be major substance P metabolites in rat striatum and it has modulatory effects similar to substance P.