THE EFFECT OF ENZYME INHIBITORS ON HISTAMINE CATABOLISM IN MAN

Abstract

The catabolism of histamine was studied in three female psychiatric patients by analysis of the [(14)C]-labelled metabolic products occurring in the urine after a subcutaneous injection of [(14)C]histamine. Each patient was studied before and during treatment with aminoguanidine or iproniazid.Without treatment the patients had a normal histamine catabolism. Aminoguanidine and iproniazid inhibited the oxidation of histamine to imidazoleacetic acid; iproniazid produed a 50% inhibition of the oxidation of methylhistamine to methylimidazoleacetic acid. After iproniazid a large proportion of the injected [C(14)]histamine was excreted as methyl [(14)C]histamine.