SUBSTANCE-P

Substance P is a potent hypotensive peptide, first noted in extracts of equine brain and intestinal tissue in 1931, that also stimulates the contraction of various intestinal tissues. Its isolation was particularly difficult and was not accomplished until 1970 following the chance finding of a sialagogic factor in bovine hypothalamic extracts. Utilizing this biological property to monitor purification procedures, the active sialagogic peptide was obtained in pure form and identified as substance P by multiple chemical and biological criteria. The amino acid sequence of substance P is H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2. Synthetic substance P was prepared and a radioimmunoassay was developed, thus facilitating well-defined research into its physiological roles. Much of the current research is centering on its possible role in sensory neurotransmission.