Effects of
antiallergic agents on 2,4-dinitrophenylated Ascaris extract (DNP-As)-induced
bronchial asthma were studied in Lewis rats, and compared with those on passive cutaneous anaphylaxis (PCA). Effects of
methysergide and
chlorpheniramine on the
bronchial asthma model were also investigated. Rats were actively sensitized with DNP-As
antigen and with killed Bordetella pertussis. After 8 d, asthmatic response was provoked by inhalation of DNP-As. The bronchomotor response was measured with a modified Konzett-Rössler method in diaphragm-sectioned rats. The inhalation of DNP-As caused a marked asthmatic bronchoconstriction without significant effect on systemic blood pressure and heart rate.
Disodium cromoglycate (DSCG), 10 mg/kg, i.v., trans-4-guanidinomethylcyclohexanecarboxylic
acid p-tert-butylphenyl
ester hydrochloride (NCO-650) and
tranilast at doses of 30 and 100 mg/kg, intraduodenally, significantly inhibited the asthmatic response.
Chlorpheniramine and
methysergide at a dose of 1 mg/kg, i.v. also significantly inhibited it. The above doses of
NCO-650 and
tranilast significantly inhibited 48 h PCA, while DSCG almost abolished the PCA. These results indicate that 1)
NCO-650 and
tranilast inhibited both the asthmatic response and PCA in almost the same degree, 2) DSCG inhibited PCA much more strongly than asthmatic response, and 3)
histamine and
5-hydroxytryptamine may be involved in this asthmatic response.