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SPECIAL REPORT Stimulation of cyclic AMP formation in the circular smooth muscle of human colon by activation of 5‐HT 4 ‐like receptors
Author(s) -
McLean Peter G.,
Coupar Ian M.
Publication year - 1996
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.1476-5381.1996.tb15182.x
Subject(s) - methysergide , stimulation , receptor , smooth muscle , agonist , chemistry , 5 ht receptor , endocrinology , medicine , serotonin , biophysics , biology , biochemistry
5‐HT stimulated cyclic AMP generation in human colonic circular smooth muscle in a concentration‐dependent fashion (EC 50 = 229.1 nM). DAU 6236 also increased cyclic AMP formation and was a partial agonist relative to 5‐HT. GR 113808 inhibited the cyclic AMP formation induced by 5‐HT with a ‐log K i value of 9.1 and an apparent pA 2 value of 9.2. Ondansetron and methysergide failed to inhibit cyclic AMP formation induced by 5‐HT. These results indicate that the 5‐HT 4 receptors of human colonic circular muscle mediate relaxation and inhibition of spontaneous contractions via formation of cyclic AMP.