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β 2 ‐Adrenoceptor blockade is the basis of guinea‐pig bronchial hyper‐responsiveness to leukotriene C 4 and other agonists
Author(s) -
Bongrani S.,
Folco G.C.,
Razzetti R.,
Schiantarelli P.
Publication year - 1983
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.1476-5381.1983.tb10527.x
Subject(s) - guinea pig , blockade , pharmacology , agonist , leukotriene , chemistry , endocrinology , medicine , biology , receptor , asthma
1 Four β‐adrenoceptor antagonists, namely (−)‐propranolol, (+)‐propranolol, ICI‐118551 and (±)‐practolol, were investigated for their effects on leukotriene C 4 (LTC 4 )‐induced bronchoconstriction in the anaesthetized guinea‐pig. (−)‐Propranolol was also investigated for its effects on acetylcholine and histamine bronchospasm in the anaesthetized guinea‐pig, and on LTC 4 ‐induced contractions of guinea‐pig isolated trachea and lung parenchyma. 2 The various β‐adrenoceptor antagonists potentiated, dose‐dependently, the bronchoconstriction induced by threshold doses of LTC 4 and the intensity of the potentiation correlated with the β 2 ‐blocking capacity possessed by the drugs. 3 (−)‐Propranolol potentiated the bronchospasm induced by threshold doses of acetylcholine and histamine but to a lesser degree than the LTC 4 ‐induced bronchospasm. 4 The airway hyper‐responsiveness induced by (−)‐propranolol was unaffected by pretreatment with mepyramine, cyproheptadine, phenoxybenzamine, atropine or indomethacin. 5 The airway hyper‐responsiveness induced by (−)‐propranolol persisted even in adrenalectomized or reserpine‐treated guinea‐pigs, although adrenalectomy induced some increase in airway responsiveness. 6 (−)‐Propranolol had no effect on LTC 4 , histamine and acetylcholine‐induced contractions of isolated trachea and lung parenchyma. 7 The results show that the airway hyper‐responsiveness induced by β‐adrenoceptor antagonists generally correlates with their β 2 ‐blocking activity. The possibility remains that some other unknown mechanism(s) may also be implicated.