INHIBITION OF DIAMINE OXIDASE PROMOTES UPTAKE OF PUTRESCINE FROM RAT SMALL-INTESTINE

In blood from the portal vein of anaesthetized rats the levels of hist amine and putrescine were 2-3-fold lower compared to arterial blood. P utrescine concentration was increased severalfold and the difference b etween portal and arterial blood abolished in animals pretreated with the specific diamine oxidase inhibitor aminoguanidine. Histamine conce ntration was 40% lower in portal compared to arterial blood in animals treated with the mast cell degranulator compound 48/80. In animals pr etreated with aminoguanidine, compound 48/80 enhanced the level of his tamine and no difference was observed between arterial and portal bloo d. The amounts of intravenously injected [C-14]-labeled histamine was about 15% lower in portal compared to arterial blood. The uptake of [C -14]-putrescine from the small intestine was estimated. In urine from animals retreated with aminoguanidine the concentration of [C-14]-putr escine was more than 40-times higher than in control animals correspon ding to a calculated uptake of about 7% in aminoguanidine treated anim als. Our results suggest that intestinal diamine oxidase clears the bl ood from diamines and prevents luminal uptake of putrescine.