Tolerance of guinea-pig airway muscle preparations to relaxant agonists induced by chronic exposure to isoprenaline in vivo.
1 The histamine sensitivities of complete tracheal spiral preparations from guinea-pigs were similar to those of paired half tracheal tissues. 2 Airway muscle preparations from animals chronically treated with isoprenaline showed a significant increase in resting tone and a significant decreased responsiveness to histamine. 3 The paired half tracheal preparations exhibited no significant difference when either their isoprenaline or theophylline sensitivities were compared. 4 Paired half tracheal muscle preparations from chronically treated animals (0.4 mumol, 4.0 mumol, and 40.0 mumol isoprenaline, 3 times daily for 21 days, s.c.) showed a significantly reduced sensitivity to isoprenaline when compared to appropriate controls. 5 Theophylline concentration-effect curves for the paired half tracheal preparations from chronically treated guinea-pigs (4.0 mumol and 40.0 mumol isoprenaline) were significantly reduced compared with appropriate controls. 5 Indomethacin treatment reversed the isoprenaline desensitization induced by chronic treatment (0.4 mumol isoprenaline) but was ineffective in animals that received the higher doses of isoprenaline in vivo.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D010276:Parasympatholytics / Q000494:pharmacology*; D011453:Prostaglandins / Q000096:biosynthesis; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D013806:Theophylline / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects*
D010276:Parasympatholytics; D011453:Prostaglandins; D011943:Receptors, Adrenergic, beta; D006632:Histamine; D013806:Theophylline; D007545:Isoproterenol; D007213:Indomethacin