title: Phosphatidylinositol responses are involved in the vascular effects of thiamylal and fentanyl.
abstract: Although thiobarbiturates potentiate, and fentanyl attenuates peripheral vasoconstriction, the intracellular mechanism involved in this phenomenon is not clear. Because smooth muscle contraction induced by alpha 1-adrenoceptor agonists is mediated by the phosphatidylinositol (PI) response, this study was carried out to clarify if thiamylal and fentanyl affect the norepinephrine-induced PI response in rat aortic slices. Rat aortic slices were incubated in Krebs-Henseleit solution containing 5 mM LiCl, [3H]myo-inositol, and varying concentrations of thiamylal or fentanyl. The Pl response was stimulated by 0.9 microM (ED50) norepinephrine (NE). The [3H]inositol monophosphate (IP1) was separated from [3H]myo-inositol by column chromatography and counted with a liquid scintillation counter. The basal IP1 accumulation was not affected by thiamylal and fentanyl. Norepinephrine-induced IP1 accumulation was potentiated by thiamylal at concentrations of 10 microM and 100 microM. Norepinephrine-induced IP1 accumulation was attenuated by 1 microM and 10 microM fentanyl. The results suggest that thiamylal stimulates the NE-induced PI response, which potentiates the vasoconstriction, and fentanyl attenuates NE-induced PI response, which would attenuate the vasoconstriction.
authors.affiliation: Department of Anesthesiology, Nagasaki University School of Medicine, Japan.
authors.forename: O
authors.initials: O
authors.lastname: Shibata
authors.forename: S
authors.initials: S
authors.lastname: Todoroki
authors.forename: Y
authors.initials: Y
authors.lastname: Terao
authors.forename: S
authors.initials: S
authors.lastname: Goto
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: T
authors.initials: T
authors.lastname: Fujigaki
authors.forename: K
authors.initials: K
authors.lastname: Sumikawa
mesh_terms: D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004357:Drug Synergism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005283:Fentanyl / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013840:Thiamylal / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D018686:Anesthetics, Intravenous; D010716:Phosphatidylinositols; D013840:Thiamylal; D005283:Fentanyl; D009638:Norepinephrine