Placental barrier permeability to Cadmium and Plumbum during cow pregnancy and at the foaling time of mares
Abstract
The paper explores placental barrier permeability to Cadmium (Cd) and Plumbum (Pb) in cows in the dynamics of their pregnancy in the direction ‘maternal blood (MB) → maternal placental compartment (MPC) → fetal placental compartment (FPC) → the umbilical cord (UC) → fetal liver (FL) → amniotic (AMF) and allantoic (ALF) fluid’ and during parturition in relatively clean and contaminated with radioactive nuclides environments, with the injection of tissue medication fetoplacentat in the dry off time, and feeding with a mixture of saponite and sulphur supplementation in rations; in mares at the foaling time in the direction ‘maternal blood (MBm) → the fetal placental compartment of a mare (FPCm) → the umbilical cord of a foal (UCf ) → the foal’s liver (FLf) → amniotic (AMFf) and allantoic (ALFf) fluid → the allantoic membrane of a foal (ALMf)’. The age of the fetus during pregnancy was established by anatomical parameters, whereas Pb and Cd levels in blood and substrates were measured by the method of atomic absorption spectrophotometry (GOST 30170896). The MPC (caruncle) and FPC (cotyledon) were analyzed separately. Their barrier function in relation to Pb and Cd was performed at its full extent in 4–5 months of pregnancy and coincided with the highest concentration in the fetal liver. Wharton’s jelly absorbed Cd in 3–4 months of gestation. With the approach of calving, Pb and Cd levels decreased in the amniotic fluid and increased in the allantoic fluid. Under the influence of fetoplacentat in MPC and FPC Cd accumulated better in AMF and ALF, whereas its levels were lower in the cortical mucus of the cervix. Pb deposited in equal concentrations in MPC of all the cows (0.46 ± 0.18 μg/kg in the contaminated environment and 0.47 ± 0.17 μg/kg in the relatively clean environment). In the relatively clean environment its levels in ALF were lower in 8 times (0.62 ± 0.16 μg/kg and 0.08 ± 0.04 μg/kg) and 26 times lower in AMF (0.52 ± 0.07 μg/kg and 0.02 ± 0.002 μg/kg), whereas Pb concentration in the cortical mucus of the cervix was 17 times lower (0.06 ± 0.03μg/kg) than that in the contaminated environment, (1.01 ± 0.28 μg/kg). Pb transited from MPC (0.46 ± 0.18 μg/kg) to FPC (0.51 ± 0.19 μg/kg), deposited in the internal environment of the uterus wherefrom it was absorbed by the cortical mucus of the cervix (1.01 ± 0.28 μg/kg). While transiting through the fetal body Pb accumulated in amniotic (0.52 ± 0.07 μg/kg) and allantoic fluid (0.62 ± 0.16 μg/kg). Mineral supplement in rations led to a weakened barrier function of MPC (0.23 ± 0.14 μg/kg), a two-fold increase of Pb in FPC (0.47 ± 0.11 μg/kg), whereas in the allantoic (0.16 ± 0.05 μg/kg) and amniotic (0.38 ± 0.10 μg/kg) fluid Pb concentration was lower when compared to the control group (0.62 ± 0.16 μg/kg; Р < 0.05 і 0.52 ± 0.07 μg/kg; Р < 0.05, respectively). Pb deposited in the cortical mucus of the cervix (2.47 ± 0.26 μg/kg; Р < 0.001). With the injection of fetoplacentat the barrier function of MPC became weaker (0.06 ± 0.01 μg/kg) than that of the control group (0.46 ± 0.17 μg/kg – 0.57 ± 0.18 μg/kg), though the decrease was exhibited less than in the cortical mucus of the cervix (0.67 ± 0.06 μg/kg). At the first stage of foaling Pb levels in mares’ blood were twice as high as Cd; in UCf Pb was not identified, Cd didn’t deposit but penetrated into the fetal liver where its levels were 11 times higher than that of Pb. Presence of Cd in allantoic fluid indicated its ability to excrete through the kidneys. Рb concentration in ALMf were 26 times higher than in the chorion and 3.7 times higher in FPCm than in ALFf. Pb levels in amniotic fluid were 1.3 times lower than in allantoic fluid and almost 4.2 times lower than in the fetal liver. Pb levels in AMF and ALF exceeded its concentration in the umbilical cord by 24.5 and 31 times respectively.
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