The role of cyclic AMP in non-adrenergic non-cholinergic contraction in guinea-pig bronchi.
1. We investigated the role of adenosine 3':5'-cyclic monophosphate (cyclic AMP) in non-adrenergic non-cholinergic (NANC) contraction in guinea-pig bronchial strips. 2. Forskolin (3 nM to 1 microM) reduced NANC contraction induced by electrical field stimulation (EFS) in a concentration-dependent fashion (-log EC50 was 7.22 +/- 0.12 M and maximum inhibition was 100 +/- 0.01%). However, forskolin (less than 1 microM) did not alter the contraction induced by substance P (SP, 1 microM). 3. Dibutyryl cyclic AMP (1 mM) also reduced NANC contractions induced by EFS (100 +/- 0.01%) without significant effect on SP (1 microM)-induced contractions. In contrast, dibutyryl cyclic GMP (1 mM) was without effect against either NANC or SP-induced contractions. 4. Both the beta 2-adrenoceptor agonist, procaterol (0.1 nM to 3 nM) and theophylline (100 nM to 1 mM) concentration-dependently reduced EFS-induced NANC contractions without significant effect on SP (1 microM)-induced contractions. 5. In contrast to forskolin, procaterol and theophylline, both sodium nitroprusside and cromakalim inhibited the EFS-induced contractions only at those concentrations that similarly reduced the contractions induced by SP (1 microM). 6. These results suggest that cyclic AMP may mediate pre-junctional inhibition of NANC contractions in guinea-pig bronchi.
Aikawa
T
T
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Sekizawa
K
K
Morikawa
M
M
Itabashi
S
S
Sasaki
H
H
Takishima
T
T
D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D001578:Benzopyrans / Q000494:pharmacology; D001980:Bronchi / Q000187:drug effects / Q000502:physiology; D001993:Bronchodilator Agents / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D019806:Cromakalim; D000242:Cyclic AMP / Q000502:physiology*; D004558:Electric Stimulation; D004983:Ethanolamines / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects; D009599:Nitroprusside / Q000494:pharmacology; D017265:Procaterol; D011758:Pyrroles / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D013806:Theophylline / Q000494:pharmacology
D001578:Benzopyrans; D001993:Bronchodilator Agents; D004983:Ethanolamines; D011758:Pyrroles; D019806:Cromakalim; D009599:Nitroprusside; D005576:Colforsin; D013373:Substance P; D003994:Bucladesine; D013806:Theophylline; D000242:Cyclic AMP; D017265:Procaterol