PT - JOURNAL ARTICLE AU - MARGARET A. CASCIERI AU - MARVIN M. GOLDENBERG AU - TEHMING LIANG TI - Biological Activity of Substance P Methyl Ester DP - 1981 Nov 01 TA - Molecular Pharmacology PG - 457--459 VI - 20 IP - 3 4099 - http://molpharm.aspetjournals.org/content/20/3/457.short 4100 - http://molpharm.aspetjournals.org/content/20/3/457.full SO - Mol Pharmacol1981 Nov 01; 20 AB - The COOH-terminal amide of substance P was replaced with a methyl ester, and the potency of this substance P methyl ester was compared with that of substance P and substance P free acid in stimulating salivation in rats and in stimulating guinea pig ileum contraction in vitro. Compared with substance P, substance P methyl ester was found to be 30% as potent in stimulating salivation and equipotent in ileum contraction. Substance P free acid was only 0.1% and 0.9% as potent as substance P in stimulating salivation and ileum contraction, respectively. The results suggest that the hydrophobicity of the COOH-terminal portion of substance P may be important for the molecule in its interaction with the substance P receptor. ACKNOWLEDGMENTS We are grateful to E. M. Subers for assistance in the guinea pig ileum assay, to Drs. E. H. Cordes and D. F. Veber for their review of the manuscript, and to Ms. Madeline Spencer for typing the manuscript.