Enzymatic and non-enzymatic defense mechanisms against active oxygen in the perinatal period

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1. The lung activities of the antioxidant enzymes (Cu, Zn-superoxide dismutase and glutathione peroxidase) were estimated on 25 autopsied cases human fetuses from 12 to 41 gestational weeks. The enzyme activities per protein concentration did not significantly change during the prenatal period but, if expressed per lung wet weight, they did show a tendency to increase from 25 gestatinal weeks.2. The bilirubin metabolism during the phototherapy for neonatal hyperbilirubinemia has been extensively studies, while the kinetics of biliverdin, one of the photooxidation products of bilirubin, has scarcely been clarified. Plasma biliverdin concentrations increased gradually after the initiation of photoirradiation, similarly as in the in vitro experiments. The relationship between the increment of the plasma biliverdin concentration during 24 hours following the start of photothrapy and the age in days of the very beginning of phototherapy revealed that the plasma biliverdin concentrations exp … More onentially decreased with age. It was concluded that the increment of the plasma biliverdin concentrations during 24 hours following the start of phototherapy reflected postnatal maturation of the biliary excretion from the hepatocyte.3. The active oxygen producing power of umbilical and maternal erythrocytes against oxidative stress was investigated using the chemiluminescence probe Cypridinal luciferin analogue (MCLA) for superoxide anion (O_2^-) generation. It was found that erythrocytes in the umbilical venous blood revealed a 2.1-fold greater maximum chemiluminescence compared to those in the maternal blood, and that chemiluminescence of the umbilical venous blood was significantly lower than that of the maternal blood upon completion of measurements.4. We examined active oxygen products during resuscitation after asphyxial load in five newborn piglets with reference to the method reported by Takahashi et al. First, this method was confirmed to be capable of measuring active oxygen in vivo and in situ. The animals were divided into two groups. was performed with 100% oxygen in one group and 21% oxygen in another group. The mean relative maximal lung surface chemiluminescence was 163(〕SY.+-.〔)47 counts in the 100% oxygen group and 47(〕SY.+-.〔)33.4 counts in the 21% oxygen group. The difference between the two groups Resuscitation was statistically significant at a level of 3% or less. This study proved that a large amount of active oxygen is produced even during ordinary resuscitation, and this fact emphasizes the necessity of sufficient precaution in oxygen administration. Furthermore, the antioxidant effect of bilirubin and urate was investigated, but the latter only proved to have a protective effect on active oxygen. Less