Involvement of diamine oxidase in catabolism of14C-putrescine in micein vivo with special reference to the formation ofγ-aminobutyric acid

Tissues of mice killed 2.5 or 30 min after injection of14C-putrescine, contained14C-γ-aminobutyric acid, an unidentified14C-compound, and unchanged14C-putrescine. In mice pretreated with aminoguanidine, a powerful inhibitor of diamine oxidase, and then with14C-putrescine, tissue levels of the radioactive catabolites,γ-aminobutyric acid and the unidentified compound were markedly reduced. The data suggest that diamine oxidase is involved in the first step of putrescine metabolism and that intestine is the main site for this step. This and other aspects of putrescine metabolism are discussed.