Effects of methylene blue and indomethacin on sodium nitroprusside-induced relaxations of the guinea pig tracheal smooth muscle.
The aim of the present investigation was to evaluate the potential modulatory effect of the guinea pig tracheal smooth muscle intrinsic tone on the relaxant responses to sodium nitroprusside and the effects of methylene blue on this response. Paired tracheal chains were mounted for isotonic contractions under 500 mg of tension in Krebs-Henseleit solution. The intrinsic modulatory tone was inhibited by indomethacin, in a concentration that did not have any effect over carbachol induced contractions. Sodium nitroprusside-induced relaxations were the same in the absence or presence of the modulatory tone. Methylene blue inhibited 50% sodium nitroprusside-induced relaxations, in the presence or absence of the intrinsic system. This suggests that sodium nitroprusside-induced relaxations are mediated through guanylyl-cyclase activation and that these are not under the modulation of the intrinsic prostaglandinergic tone.
Department of Anatomy, Faculty of Medical Sciences, Campinas State University, SP, Brazil.
M J
MJ
Marques
H
H
Santo Neto
U M
UM
Meirelles
D000818:Animals; D002217:Carbachol; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors*; D006168:Guinea Pigs; D007213:Indomethacin / Q000494:pharmacology*; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology*; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009599:Nitroprusside; D014132:Trachea / Q000187:drug effects*
D016861:Cyclooxygenase Inhibitors; D009599:Nitroprusside; D002217:Carbachol; D006162:Guanylate Cyclase; D008751:Methylene Blue; D007213:Indomethacin