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Rapid degradation of [ 3 H]‐substance P in guinea‐pig ileum and rat vas deferens in vitro
Author(s) -
Watson Stephen P.
Publication year - 1983
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1983.tb11029.x
Subject(s) - vas deferens , ileum , substance p , guinea pig , medicine , agonist , endocrinology , chemistry , receptor , in vitro , biology , biochemistry , neuropeptide
1 The degradation of [ 3 H]‐substance P was monitored in guinea‐pig ileum and rat vas deferens. Substantial and rapid metabolism occurred in both tissues within the time course of the pharmacological responses; for example, after 1 min more than 50% of the extracted tritium from both tissues was present in the form of metabolites. 2 [ 3 H]‐inulin was used to estimate the rate of equilibration of the extracellular space of guinea‐pig ileum longitudinal muscle and rat vas deferens with the bath fluid; half‐lives of 30 s and 5 min respectively were observed. 3 These two factors combine to give different concentrations of substance P in the biophase of the tissues. The peak concentration of substance P reached in the guinea‐pig ileum longitudinal muscle was approximately five times higher than in the rat vas deferens. 4 An analogue of substance P, [ 3 H]‐DiMe‐C7, was found to be stable in both tissues. 5 These results are discussed in the light of the suggested existence of multiple receptors for substance P, based on agonist potency differences.