Total antioxidant capacity of bovine spontaneously released and retained placenta.

Exposure of living organisms to a constant generation of reactive oxygen species (ROS) resulted in the development of antioxidative defence systems which protect cells and tissues against their harmful effects. The retention of fetal membranes (RFM) in cows is hypothesized to be connected with the imbalance between production and neutralization of ROS. The efficiency of enzymatic and non-enzymatic antioxidative systems can be detected by the determination of single components of this system or by so-called total antioxidant capacity (TAC). In the present study, total antioxidant capacity was compared with previously measured parameters of antioxidative defence mechanisms in placental tissues of cows with respect to time of fetal membranes expulsion and mode of delivery. Placental samples were divided into: (A) caesarian section before term (272-277 days of pregnancy) without RFM (n=9), (B) caesarian section before term with RFM (n=14), (C) caesarian section at term (282-288 days of pregnancy) without RFM (n=12), (D) caesarian section at term with RFM (n=16), (E) spontaneous delivery at term without RFM (n=8), (F) spontaneous delivery at term with RFM (n=8). TAC was measured spectrophotometrically at 593nm by use of 2,4,6-tri-pyridyl-s-triazine in homogenates of maternal and fetal part of placenta and expressed as mumol/g protein (mean+/-S.E.M.). The values of TAC were significantly higher (P</=0.05) in the fetal than in maternal part in preterm samples (A - maternal: 27.24+/-4.17mumol/g prot, fetal: 63.67+/-18.16, B - maternal: 49.80+/-5.11, fetal: 70.96+/-13.23). The opposite relationship was noticed in term samples. Significantly higher values were observed in retained than in not retained placental tissues (C - maternal: 32.40+/-6.12, fetal: 16.29+/-3.97, D - maternal: 48.17+/-6.91, fetal: 27.92+/-4.72, E - maternal: 40.55+/-2.66, fetal: 27.90+/-1.23, F - maternal: 45.85+/-6.40, fetal: 43.50+/-4.61). Values of TAC are comparable with previously determined single parameters of antioxidative defence mechanisms in placental tissues and may be of clinical importance. Whether they reflect plasma values as well requires further evaluation.