Abstract
In a previous study on diamine oxidase activity of amniotic fluid (4) it was questioned whether enzyme inhibition with an intramuscular injection of aminoguanidine sulphate was due to a passage of the inhibitor to the amniotic fluid or was secondary to enzyme inhibition in the maternal blood. In the present investigation amniotic fluid was sampled from 23 women in the second trimester of gestation. In 15 cases, aminoguanidine sulphate was given 1 hour before sampling. In 5 cases aminoguanidine sulphate was detected in the amniotic fluid by thin layer chromatography and a subsequent staining technique. In 10 cases the presence of a diamine oxidase inhibitor in the amniotic fluid was shown by observing the effect of this amniotic fluid on venous plasma with a high diamine oxidase activity. When aminoguanidine sulphate was not given, the amniotic fluid did not show such inhibitory effects. Nor did the incubation itself inhibit the enzyme.