title: Response of bronchial smooth muscle to mast cell degranulation in situ.
abstract: We studied the response of bronchial smooth muscle to mast cell degranulation with Ascaris suum antigen (AA) and compound 48/80 (48/80) in 26 mongrel dogs in situ. Bronchial smooth muscle response was measured isometrically in situ from a segment of the right middle lobe bronchus; tracheal response was monitored isometrically as a control. After intra-arterial (ia) injection of AA into the bronchial circulation, bronchial contraction preceded tracheal contraction by 19.2 +/- 4.6 s (P less than 0.002). Bronchial contraction to AA (21.7 +/- 3.4 g) was substantially greater than to 48/80 (10.5 +/- 1.8 g, P less than 0.05) corresponding to differences in maximal systemic histamine concentrations (146 +/- 24.1 vs. 1000 +/- 236 ng/ml, P less than 0.01). In 5 dogs, the effect of leukotriene D4 (LTD4) and FPL 55712 was studied. Injection of 10(-8) mol ia LTD4 caused no bronchial contraction. In four dogs, 10(-7) mol FPL 55712 caused no bronchial relaxation after initial precontraction during immune degranulation with AA; intravenous chlorpheniramine (5 mg/kg) caused 69.7 +/- 9.4% relaxation. We demonstrate a model that permits selective immune degranulation of a single major resistance bronchus in situ. We conclude that AA-induced degranulation in dogs caused bronchial contraction predominantly by secretion of preformed mediator.
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology; D001200:Ascaris / Q000276:immunology; D001696:Biomechanical Phenomena; D001980:Bronchi / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D004285:Dogs; D005260:Female; D006632:Histamine / Q000097:blood; D008297:Male; D008407:Mast Cells / Q000276:immunology / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D000941:Antigens; D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine