Neurogenic "off" contractions are mediated by NK2-receptors in the circular muscle of guinea pig ileum.
In guinea pig ileal circular muscle, electrical stimulations by a train of 10-100 pulses (0.05-msec duration, 10 Hz) produced tetrodotoxin-sensitive "off" contractions that were initiated upon the termination of stimulations. Atropine at 10(-6) M did not inhibit the "off" contractions. FK224 at 10(-5) M, a dual antagonist for NK1- and NK2-receptors, but not 10(-7) M CP-96,345, an antagonist for NK1-receptors, almost abolished the "off" contractions in the presence of atropine. These results suggest that the neurogenic "off" contraction was mediated mainly by NK2-receptors in the circular muscle of guinea pig ileum.
Suzuki
N
N
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Mizuno
K
K
Gomi
Y
Y
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004558:Electric Stimulation; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000294:innervation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000294:innervation* / Q000648:ultrastructure*; D010456:Peptides, Cyclic / Q000494:pharmacology; D018041:Receptors, Neurokinin-2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D013373:Substance P / Q000037:antagonists & inhibitors
D010456:Peptides, Cyclic; D018041:Receptors, Neurokinin-2; C075570:FK 224; D013373:Substance P; D001285:Atropine