[Histamine concentration in arterial plasma in the course of repeated antigen challenges of the bronchopulmonary system. Second communication (author's transl)].

Repeated ascaris extract (A.E.) exposure on dogs sensitized against this allergen at intervals of 90, 180, and 360 min is followed by different increases in the histamine concentration in the arterial plasma. At 90 min, a significantly smaller amount of histamine becomes measurable in the arterial plasma. Edyn increases unproportionally strong. One hundred eighty minutes after the first exposure A.E. inhalation is again followed by a clearly increased histamine concentration in the arterial plasma. Edyn still increases unproportionally strong. Three hundred sixty minutes after the first A.E. exposure another exposure revealed a stronger increase in the histamine concentration in the arterial plasma, the Edyn increase being smaller than at the first exposure. These results are of importance with regard to the sensitivity of the airways and the investigation of antiallergic and bronchospasmolytic drugs.