Anaphylaxis in the guinea‐pig isolated heart: selective inhibition by burimamide of the positive inotropic and chronotropic effects of released histamine

Abstract

1 Anaphylaxis was induced in the isolated heart of the guinea-pig in the presence of burimamide at concentrations of 4 × 10⁻⁵M and 2·7 × 10⁻⁴M. 2 Burimamide did not affect the immunological release of histamine; however, it selectively antagonized the positive inotropic and chronotropic effects of released histamine. The antagonism of the positive chronotropic effect was concentration-dependent. 3 Neither the negative dromotropic effect nor the decrease in coronary flow rate occurring during anaphylaxis were inhibited by burimamide. 4 The results are in agreement with the double histamine receptor theory and suggest that, in the heart of the guinea-pig, H₂-receptors are involved in the positive inotropic and chronotropic effects of released histamine, and H₁-receptors in the negative dromotropic effect.