title: Hypothermia enhances contractile responses of the guinea pig taenia caeci to acetylcholine, 5-hydroxytryptamine, caffeine and calcium.
abstract: Isometric contraction of isolated guinea-pig taenia caeci was induced with acetylcholine (ACh) and 5-hydroxytryptamine (5-HT) at 37 and 30 degrees C to investigate the effect of hypothermia on the response of smooth muscle to neurotransmitters. Lowering the temperature increased the amplitude of contraction in response to 10(-6) M ACh. Contraction in response to 10(-6) M 5-HT was also greater at 30 degrees C. 5-HT-contraction was not inhibited by atropine, but was inhibited by ketanserin. Calcium-contraction was also induced in an isosmotic high potassium solution. The amplitude of the contraction elicited by 5 x 10(-3) M Ca was significantly greater at 30 degrees C, and was inhibited by verapamil. The amplitude of the contractile response to 5 x 10(-3) M caffeine was also greater at 30 degrees C than at 37 degrees C. The finding that both calcium- and caffeine-contraction were enhanced at low temperature raises the possibility that intracellular calcium participate in cold-induced enhancement of contraction.
authors.affiliation: Department of Physiology, Medical University of Yamanashi, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nagai
authors.forename: H
authors.initials: H
authors.lastname: Inada
authors.forename: K I
authors.initials: KI
authors.lastname: Kawabata
authors.forename: R
authors.initials: R
authors.lastname: Ohura
authors.forename: M
authors.initials: M
authors.lastname: Iriki
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D002432:Cecum / Q000187:drug effects / Q000502:physiology*; D003080:Cold Temperature; D003470:Culture Media; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D012701:Serotonin; D002110:Caffeine; D000109:Acetylcholine; D002118:Calcium