Acetylcholine-induced bronchoconstriction modified by noise exposure in normal but not in sensitized guinea-pigs.
1. The acute (6h) exposure of guinea-pigs to white noise (110 dB) as a stress stimulus, reduced bronchial reactivity to acetylcholine (Ach) (3-1000 micrograms kg-1 i.v.) in anaesthetized animals. 2. The hyporesponsiveness to Ach in stressed animals was not confirmed in vitro on tracheal preparations (Ach 1 x 10(-9)-1 x 10(-4) g ml-1) and disappeared in vivo when the animals were sensitized with ovalbumin (OA, 100 mg kg-1 i.p. + 100 mg kg-1 s.c.). The hyporesponsiveness was also absent in ovalbumin sensitized guinea-pigs exposed to an aerosol of ovalbumin 60 min before testing with Ach. 3. In non-sensitized guinea-pigs, pretreatment with butoxamine (1 mg kg-1 i.v.) or with theophylline (25 mg kg-1 i.v.), completely abolished the effect of noise-exposure. In contrast, pretreatment with L-NG-nitro-arginine methyl ester (L-NAME, 10 mg kg-1 i.v.), alpha-chymotrypsin (2 U kg-1 i.v.) or with enprofylline (10 mg kg-1 i.v.), did not affect it. 4. In conclusion, our experiments reveal inhibitory mechanisms upon Ach-induced bronchoconstriction activated by a stress stimulus and this is absent in sensitized animals. These mechanisms seem to be linked to the adrenergic beta 2-receptors and a role for the purinergic system (via A-receptors) may also be present.
Nieri
P
P
Institute of Biological Sciences, Faculty of Pharmacy, Pisa, Italy.
Lazzeri
N
N
Martinotti
E
E
Scatizzi
R
R
Breschi
M C
MC
D000109:Acetylcholine / Q000494:pharmacology*; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000941:Antigens / Q000008:administration & dosage; D016084:Bronchoconstriction / Q000187:drug effects* / Q000502:physiology; D001993:Bronchodilator Agents / Q000494:pharmacology; D002078:Butoxamine / Q000494:pharmacology; D002918:Chymotrypsin / Q000494:pharmacology; D006168:Guinea Pigs; D007114:Immunization; D066298:In Vitro Techniques; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009622:Noise / Q000009:adverse effects*; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology; D010275:Parasympathetic Nervous System / Q000502:physiology; D013312:Stress, Physiological / Q000503:physiopathology; D013806:Theophylline / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000502:physiology; D014970:Xanthines / Q000494:pharmacology
D000941:Antigens; D001993:Bronchodilator Agents; D014970:Xanthines; D002078:Butoxamine; D010047:Ovalbumin; D013806:Theophylline; C034347:enprofylline; D002918:Chymotrypsin; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester