Modification by indomethacin of airway contractile responses in normal and sensitized guinea-pigs

Active sensitization of guinea-pig resulted in an increase in responsiveness and sensitivity of tracheal and lung arenchymal strips to CaCl 2 (in K +-depolarized tissue), KCl, acetylcholine and histamine. Indomethacin (5 μM) preferentially enhanced the response of tracheal strips from normal animals to histamine and to a lesser extent acetylcholine but not to CaCl 2 or KCl. A similar trend was observed in sensitized tissues. Indomethacin pretreatment did not cause changes in responsiveness or sensitivity of lung parenchymal strips from normal or sensitized guinea-pigs to the agonists tested. It is concluded that immunological sensitization produced a non-specific hyperresponsiveness in trachea and lung parenchymal strips. Conversely, cyclooxygenase inhibition by indomethacin elicited a selective increase in the responsiveness to certain agonists in central but not in the peripheral airways.