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Cholinergic mechanisms and bronchoconstriction in guinea-pigs
1Institut Léon Fredericq, Physiologie, Université de Liège, Belgique.
Summary
Peripheral cholinergic mechanisms do not significantly influence histamine or anaphylactic bronchoconstriction in guinea-pigs. Vagotomy and atropine did not alter direct bronchial responses to histamine or antigen.
Area of Science:
- Pharmacology
- Respiratory Physiology
Background:
- Bronchoconstriction is a key feature of respiratory diseases.
- The role of peripheral cholinergic mechanisms in mediating bronchoconstriction, particularly during anaphylaxis, requires further elucidation.
Purpose of the Study:
- To investigate the role of peripheral cholinergic mechanisms in mediating bronchoconstriction.
- To assess the impact of vagotomy and cholinergic blockade on responses to acetylcholine, histamine, and antigen in sensitized guinea-pigs.
Main Methods:
- Active sensitization of guinea-pigs against ovalbumin.
- Bilateral cervical vagotomy and cholinergic efferent blockade using atropine.
- Quantification of bronchoconstriction via dose-threshold for respiratory asynchronism, total lung resistance, and dynamic compliance under controlled ventilation.
Main Results:
- Vagotomy did not significantly affect bronchial responses to histamine, acetylcholine, or antigen.
- Atropine did not alter direct bronchial responses to histamine.
- Higher doses of atropine showed a trend towards decreased bronchial sensitivity to antigen, possibly due to repeated antigen administration.
Conclusions:
- Peripheral cholinergic mechanisms play no significant role in histamine- or anaphylaxis-induced bronchoconstriction in guinea-pigs.
- Curarization does not influence resting bronchial tone.