title: Airway responses to histamine and methocholine in Ascaris suum-allergic rhesus monkeys.
abstract: We performed dose-response curves to inhaled histamine (H) and methacholine (MC) in a group of eight rhesus monkeys, with and without natural allergy to Ascaris suum antigen (AA). The animals were anesthetized with pentobarbital sodium, 25 mg/kg im and studied in a volume-displacement body plethysmograph. The dose of H or MC producing a 50% increase in pulmonary resistance (RL) was used to determine sensitivity to these agents and the increase in RL at a given dose was employed as a measure of reactivity. Sensitivity and reactivity to H and MC were then compared with AA responsiveness. A wide range of responses was observed but allergic animals were not more sensitive or reactive to H or MC than nonallergic animals. In addition, we studied the changes in breathing pattern that occurred during the inhalation of AA, H, and MC in four AA-sensitive animals. AA and H produced rapid shallow breathing within 30 s of starting inhalation, but MC, despite causing an equal degree of bronchoconstriction, did not produce alterations in breathing pattern.
mesh_terms: D000336:Aerosols; D000818:Animals; D000941:Antigens / Q000008:administration & dosage*; D001200:Ascaris / Q000276:immunology; D001249:Asthma / Q000503:physiopathology; D001986:Bronchial Spasm / Q000503:physiopathology*; D005652:Functional Residual Capacity; D000882:Haplorhini; D006632:Histamine / Q000494:pharmacology*; D008168:Lung / Q000502:physiology*; D008251:Macaca / Q000276:immunology*; D008253:Macaca mulatta / Q000276:immunology*; D008688:Methacholine Compounds / Q000494:pharmacology*; D012882:Skin Tests
chemical_list: D000336:Aerosols; D000941:Antigens; D008688:Methacholine Compounds; D006632:Histamine