1 In this study, the role of neuropeptides in antigen-induced bronchoconstriction and bronchial responsiveness in guinea-pigs was evaluated by use of phosphoramidon, the inhibitor of neutral

These results indicate that the degree of respiratory failure influences the degree of decrease in oxygen saturation during gastroscopy. It is suggested that use of the nasal route for oxygen supply may be one of the major causes of the hypoxemia.

These results suggest that tachykinins, at least substance P, are involved in a part of the UNDW-induced bronchoconstriction in our guinea-pig model.

1 Inhalation of ultrasonically nebulized distilled water (UNDW) can induce bronchoconstriction only in asthmatics, but mechanisms of the response are not well known. We recently reported a guinea-pig model of UNDW-induced bronchoconstriction (UNDW-IB) in which UNDW induces bronchoconstriction when UNDW is inhaled 20 min after a challenge with aerosolized ovalbumin (OA) in passively sensitized, anaesthetized and arti®cially ventilated guinea-pigs. 2 To elucidate the role of histamine in the UNDW-IB, we examined the eects of antihistamines, diphenhydramine hydrochloride (DH) and chlorpheniramine maleate (CP), and measured histamine content in bronchoalveolar lavage¯uid (BALF) in the animal model. 3 DH in doses of 0.1, 1.0 and 10 mg kg 71 and CP in doses of 0.01, 0.1 and 1.0 mg kg 71 administered intravenously 15 min after the OA challenge partially reduced the UNDW-IB at 1 and 2 min after the UNDW inhalation in a dose-dependent manner. Histamine content in BALF recovered 10 min after the UNDW inhalation following the OA provocation was signi®cantly increased compared with that after saline inhalation and before the UNDW inhalation following the OA challenge. 4 Intravenous atropine in a dose of 0.5 mg kg 71 or inhaled disodium cromoglycate in concentrations of 1 and 10 mg ml 71 did not alter the UNDW-IB. 5 These results suggest that histamine is involved in part in the UNDW-IB in our animal model.

These results suggest that in vivo airway eosinophils may reduce non-specific bronchial responsiveness through inhibitory or bronchoprotective prostanoids.