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The pharmacology of sheep tracheobronchial muscle: a relaxant effect of histamine on the isolated bronchi
Author(s) -
EYRE P.
Publication year - 1969
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1969.tb07997.x
Subject(s) - mepyramine , histamine , methysergide , atropine , acetylcholine , endocrinology , stretch receptor , medicine , bradykinin , isoprenaline , chemistry , pharmacology , receptor , biology , serotonin , antagonist , stimulation
1 Histamine contracted the tracheal and major bronchial muscles of sheep and relaxed the muscles of the lesser bronchi and bronchioles. 2 The stimulant action of histamine on the trachea was antagonized by mepyramine, whereas the relaxant effect on the bronchial tree was not. 3 5‐Hydroxytryptamine contracted the musculature from all parts of the respiratory tract—an effect which was specifically antagonized by both methy‐sergide and atropine. 4 Acetylcholine contracted all sheep tracheobronchial muscle and isoprenaline relaxed it. 5 Bradykinin had a very weak stimulant action. 6 It is concluded that histamine relaxes sheep bronchi by a direct excitation of histamine‐sensitive receptors which are not blocked by mepyramine. No indirect components through autonomic nervous elements or by way of catecholamine release were evident. 5‐Hydroxytryptamine seemed to have a dual mode of action in contracting sheep tracheobronchial muscle ( a ) directly on its own receptors and ( b ) indirectly through parasympathetic components.