The relation between effects of adenosine, theophylline and enprofylline on the contractility of sensitized guinea-pig lung strips.
Contractile responses of lung parenchymal strips from ovalbumin-sensitized guinea-pigs to cumulative addition of antigen were significantly potentiated by 10 min pretreatment with adenosine 10 microM. This potentiation was unaffected by the adenosine uptake inhibitor, dipyridamole, 2 microM. Cumulative addition of adenosine 0.1-100 microM to parenchymal strips without antigen produced variable responses, unrelated to sensitization, some contracting, some relaxing. Theophylline 100 microM caused relaxation of parenchymal strips and significantly inhibited the antigen-induced contraction with a parallel shift of the log concentration-response line. It also inhibited the adenosine-induced potentiation of contraction. Enprofylline 100 microM caused a greater relaxation of the tissue than theophylline. While it inhibited the adenosine-induced potentiation of the response, enprofylline, in contrast to theophylline, failed to inhibit the antigen-induced contraction of guinea-pig parenchyma. At these concentrations, theophylline and enprofylline each inhibited the antigen-induced release of SRSA (leukotrienes C4, D4 and E4), and of histamine, from sensitized guinea-pig lung fragments.
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D000941:Antigens / Q000276:immunology; D001993:Bronchodilator Agents / Q000494:pharmacology*; D004176:Dipyridamole / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006636:Histamine Release / Q000187:drug effects; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D012132:Respiratory Muscles / Q000187:drug effects; D013189:SRS-A / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology*; D014970:Xanthines / Q000494:pharmacology*
D000941:Antigens; D001993:Bronchodilator Agents; D013189:SRS-A; D014970:Xanthines; D004176:Dipyridamole; D013806:Theophylline; C034347:enprofylline; D000241:Adenosine