Studies on the mechanism of anaphylaxis in the rat

Abstract

Rats rendered susceptible to sensitization and to histamine by the administration of HPV were studied in regard to anaphylaxis, histamine toxicity, the concentration of histamine, and the activity of diamine oxidase in the blood. Histamine injected intravenously into normal and sensitized rats did not result in the release of diamine oxidase into the blood. The concentration of histamine in the blood, the release of histamine into the blood during anaphylaxis, and the destruction of histamine in the blood of shocked rats were not altered by the administration of cortisone at the time of sensitization, during mid-sensitization, or just prior to challenge. Cortisone administered to rats treated with HPV at the time of sensitization had no effect on the subsequent anaphylactic reaction. Cortisone administered just prior to challenge with the antigen afforded considerable protection against anaphylaxis. Cortisone administered with HPV greatly increased the rat's susceptibility to histamine toxicity. Cortisone administered just prior to challenge with histamine had a slight protective effect against histamine toxicity. Pretreatment of sensitized rats with aminoguanidine caused an increase in the concentration of histamine in the blood both before and during anaphylactic shock and inhibited the destruction of histamine in the shocked blood. Pretreatment of the rat with aminoguanidine had no effect on the severity of anaphylactic shock.