Diamine Oxidase (Histaminase) and Heparin Inhibition of Gastric Secretion in Man

Abstract

In 5 healthy volunteers and in 3 patients with urticaria pigmentosa, the basal gastric acid output and the blood plasma diamine oxidase (DAO) activity were studied under basal conditions and after i.v. injection of 10,000 to 20,000 IU of heparin. A significant inhibition of the gastric basal secretion occurred among the normal subjects and in one of the patients. The maximal gastric inhibition occurred simultaneously with the maximal DAO activity in blood plasma. In two healthy subjects, the inhibition was abolished by administra tion of aminoguanidine. When stimulated by continuous i. v. injection of histamine in submaximal dose (0.6 μg base/kg body wt. and h), however, the gastric output seemed to be uninfluenced by heparin, even in large doses. Our findings agree with the possibility that DAO may mediate the inhibitory effect of heparin on the gastric secretion.

Key Words:

• Aminoguanidine
• blood plasma
• diamine oxidase/histaminase (B.C. 1.4.3.6.)
• gastric juice
• heparin
• histamine
• urticaria pigmentosa