Effects of substance P antagonists on the atropine-sensitive and atropine-resistant responses of guinea-pig ileum to substance P.
The effects of substance P (SP) antagonists on the atropine-sensitive and atropine-resistant responses to SP of guinea-pig isolated ileum were investigated. The atropine-resistant response to SP was the contractile response on untreated preparations, and the atropine-sensitive response was the response to high concentrations of SP (5 X 10(-7) M) on preparations desensitized to SP with a concentration of SP of 3 X 10(-7) M. The SP antagonists tested, (D-Pro2,D-Phe7,D-Trp9)-SP, (D-Pro2,D-Trp7,9)-SP, (D-Arg1,D-Pro2,D-Trp7,9,Leu11)-SP and (D-Arg1,D-Trp7,9,Leu11)-SP (spantide), did not have similar orders of potency on the atropine-sensitive and atropine-resistant responses to SP, spantide being more potent than the other antagonists on the atropine-resistant response but no more potent on the atropine-sensitive response than (D-Pro2,D-Phe7,D-Trp9)-SP or (D-Arg1,D-Pro2,D-Trp7,9,Leu11)-SP. These findings are consistent with the hypothesis that neuronal receptors for SP differ from those on smooth muscle in guinea-pig ileum.
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D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D002799:Cholinergic Fibers / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation*; D036341:Intercellular Signaling Peptides and Proteins; D009119:Muscle Contraction / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000187:drug effects; D013373:Substance P / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; C016116:substance P-like peptides; D013373:Substance P; D001285:Atropine; D000109:Acetylcholine