Non-specific stimulant activity of tyramine on isolated intestinal preparations

The effect of tyramine on isolated organ preparations from several animal species has been studied. Contraction of the guinea-pig ileum by tyramine is due to a direct effect on histamine receptors whereas the contractile effect on the rat fundus and rabbit jejunum by tyramine is mediated through 5-hydroxytryptamine receptors. These studies indicate the variability and non-specificity of isolated organ responses and that the effects of tyramine are not limited to adrenergic systems.