The effect of H2-blocking agents on systemic anaphylaxis in guinea pigs.

Theoretically, histamine H2 antagonists could aggravate allergic bronchoconstriction (1) by increasing mediator release, and (2) by blocking histamine-induced bronchodilatation. We measured dynamic compliance, subdivisions of lung volume, and mortality in immunized guinea pigs after parenteral administration of antigen, with and without pretreatment with the H2-blocking agents cimetidine and metiamide. Administration of antigen caused significant mortality as well as decreases in dynamic compliance, total lung capacity, and vital capacity and increases in functional residual capacity. The prior administration of cimetidine or metiamide did not protect against or enhance these effects of antigen challenge.