title: Effects of methylene blue on the development of intrinsic contractile responses of the guinea pig tracheal smooth muscle.
abstract: The aim of the present study was to investigate the effects of methylene blue, a guanylyl cyclase inhibitor, on the development of intrinsic contractile responses of the guinea pig tracheal smooth muscle. Paired tracheal chains were mounted for isotonic contractions under 500 mg of tension in Krebs-Henseleit solution. The intrinsic contractile tone modulated carbachol-induced contractions and was inhibited by indomethacin, suggesting the involvement of cyclooxygenase products on this tone. Methylene blue (5 x 10(-5)M) irreversibly inhibited the intrinsic contractile responses. Considering that methylene blue prevents any endogenous production of cGMP, it would be expected to enhance the contractions. However, since methylene blue has effects over nitric oxide synthase and nitric oxide itself, we suggest that guanylyl cyclase activation is not important for the development of the intrinsic tone.
authors.affiliation: Dept. of Anatomy, Campinas State University, SP, Brazil.
authors.forename: M J
authors.initials: MJ
authors.lastname: Marques
authors.forename: H
authors.initials: H
authors.lastname: Santo Neto
authors.forename: U M
authors.initials: UM
authors.lastname: Meirelles
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D011451:Prostaglandin-Endoperoxide Synthases; D014132:Trachea
chemical_list: D004791:Enzyme Inhibitors; D011451:Prostaglandin-Endoperoxide Synthases; D006162:Guanylate Cyclase; D008751:Methylene Blue