Studies on Diamine Oxidase Activity During Pregnancy

Abstract

The diamine oxidase activities (diamine: oxygen oxidoreductase (deaminating), (EC 1.4.3.6)) of amniotic fluid, maternal venous plasma and fetal plasma were measured in 19 pregnant women at term. No statistically significant difference was found between the enzyme activity of the amniotic fluid and the maternal plasma. The enzyme activity in the fetal circulation was approximately one hundredth of that in the other compartments. It is suggested that passage of fluid through the amniotic membrane might be of greater importance in the formation of the amniotic fluid than believed earlier. Twenty‐seven women in the second trimester of pregnancy were also investigated, maternal venous blood and amniotic fluid being sampled. The diamine oxidase activity of the amniotic fluid was significantly lower than that of the maternal plasma. It is suggested that the mechanisms governing the production of amniotic fluid might vary in importance at different periods of gestation. Following intramuscular injection of aminoguanidine, a diamine oxidase inhibitor, in 10 pregnant women significantly lower enzyme activity was found in both maternal plasma and in amniotic fluid than in nontreated subjects.