Arginase activity is important in polyamines and nitric oxide production which are required for the normal growth of placenta and embryo. A considerable arginase activity is observed in amniotic fluid in women at the end of pregnancy. Lecithin to sphingomyelin (L/S) ratio is widely used in order to assess fetal lung immaturity and prevention of neonatal respiratory distress syndrome, the major cause of neonatal morbidity and mortality. The purpose of our study was to determine if there is a relationship between arginase activity and L/S ratio in amniotic fluid. The study included 170 pregnant women, 18-43 years old, with normal and pathological pregnancy. The arginase activity was measured on the basis of the determination of the amount of liberated ornithine from arginine as substrate. The L/S ratio was done by using a thin layer chromatography. Increased level of arginase activity correlates with the fetal lung maturity. Arginase activity and L/S values may be useful biochemical data, for intrauterine baby maturity.

Background: During the pregnancy the amount of polyamines spermine, spermidine and putrescine, rise rapidly in amniotic fluid. Polyamine oxidase (PAO) represents one of the key enzymes in catabolic pathway of polyamines. PAO catalyzes the oxidative deamination of spermine (Sp) or spermidine (Spd). The literature data documented that serum PAO activity increases in pregnancy. Diamine oxidase (DAO), histaminase, catalyses the oxidation of diamine putrescine or histamine. DAO is present in high concentrations in amniotic fluid. Amniotic fluid is the protective liquid for the baby in the mother's uterus. The determination of the lecithin to sphyngomyelin (L/S) ratio is by far the most widely used and accepted method to assess the fetal lung immaturity. The idea of the present study was to elucidate the polyamine metabolism in amniotic fluid during the pregnancy, through investigation of polyamine oxidase (PAO) and diamine oxidase (DAO) activities, and to compare their activities with the values of lecithin/ sphingomielin ratio (L/S) ratio. Methods: The study included 170 pregnant women. The amniotic fluid samples were obtained using amniocentesis. The values of L/S ratio were estimated by a thin layer chromatography. PAO and DAO activities were measured by the spectrophotometric methods. Results: Our results confirmed that amniotic fluid possess PAO and DAO activity. The activities of both enzymes in amniotic fluid samples increase in parallel with the L/S ratio increase. Diamine oxidase activity was higher than polyamine oxidase activity. Conclusions: DAO and PAO activities may serve as markers of fetal lung maturity.