ABSTRACT
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.
Subject(s)
Cyclooxygenase Inhibitors/pharmacology , Guanylate Cyclase/antagonists & inhibitors , Indomethacin/pharmacology , Methylene Blue/pharmacology , Muscle Relaxation/drug effects , Muscle, Smooth/drug effects , Trachea/drug effects , Animals , Carbachol , Guinea Pigs , Male , NitroprussideABSTRACT
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 per cent sodium nitroprusside-induced relaxations, in the presence or absence of the intrinsic system. This suggests that sodium nitroprusside-induced relaxations are mediated through guanylyl-cylase activation and that these are not under the modulation of the intrinsic prostaglandinergic tone. (AU)
Subject(s)
Animals , Guinea Pigs , Male , Comparative Study , Methylene Blue/pharmacology , Indomethacin/pharmacology , Cyclooxygenase Inhibitors/pharmacology , Guanylate Cyclase/antagonists & inhibitors , Muscle, Smooth/drug effects , Trachea , Muscle Relaxation/drug effects , Carbachol , NitroprussideABSTRACT
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 per cent sodium nitroprusside-induced relaxations, in the presence or absence of the intrinsic system. This suggests that sodium nitroprusside-induced relaxations are mediated through guanylyl-cylase activation and that these are not under the modulation of the intrinsic prostaglandinergic tone.
Subject(s)
Animals , Guinea Pigs , Male , Cyclooxygenase Inhibitors/pharmacology , Guanylate Cyclase/antagonists & inhibitors , Indomethacin/pharmacology , Methylene Blue/pharmacology , Muscle Relaxation/drug effects , Muscle, Smooth/drug effects , Trachea , Carbachol , NitroprussideABSTRACT
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.
Subject(s)
Enzyme Inhibitors/pharmacology , Guanylate Cyclase/antagonists & inhibitors , Methylene Blue/pharmacology , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Animals , Guinea Pigs , In Vitro Techniques , Male , Prostaglandin-Endoperoxide Synthases , TracheaABSTRACT
The aim of the present study was to investigate the effects of methylene bue, 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 (5x10(-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 activations is not important for the development of the intrinsic tone. (AU)
Subject(s)
Animals , Male , Guinea Pigs , RESEARCH SUPPORT, NON-U.S. GOVT , In Vitro Techniques , Methylene Blue/pharmacology , Guanylate Cyclase/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Trachea , Prostaglandin-Endoperoxide SynthasesABSTRACT
The aim of the present study was to investigate the effects of methylene bue, 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 (5x10(-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 activations is not important for the development of the intrinsic tone.
