Inhibition of antigen-induced lung anaphylaxis in the guinea-pig by BN 52021 a new specific paf-acether receptor antagonist isolated from Ginkgo biloba.

Paf-acether appears to be a potent mediator released in response to allergen exposure in sensitized animals and it could contribute to clinical manifestations of allergic asthma. In order to ascertain this assumption the inhibition of antigen-induced lung anaphylaxis in guinea-pig by BN 52021, a new highly specific paf-acether antagonist, was studied. Ovalbumin injected into passively sensitized guinea-pig induced a large bronchoconstriction which was accompanied by thrombocytopenia and leukopenia. Treatment of animals with BN 52021 i.v., five minutes before challenge, strongly (at the doses of 1 and 2 mg/kg) or totally (at 0.1 mg/kg) inhibited the bronchoconstriction and partially reduced the thrombocytopenia and leukopenia the thrombocytopenia occurring after challenge. These results confirm that paf-acether and platelets might play a key role in asthma. BN 52021 and other paf-acether antagonist could provide a new group of potent prophylactic anti-asthma drugs.