Low environmental contamination by lead in pregnant women: effect on calcium transfer in human placental syncytiotrophoblasts.

There is an extensive literature on the neurotoxic effects of lead (Pb) on the developing fetus; however, little is known about the mechanisms of action at low levels. Heavy metals are known to affect calcium (Ca2+) homeostasis through perturbation of Ca2+ channels and pumps and interference with protein kinase C (PKC) and Ca2+ binding protein (CaBP). During pregnancy, placental Ca2+ exchange is one of the most important mechanisms for fetal survival. This ion is an essential element for healthy fetal growth and development. The aim of the present study was to determine the influence of low maternal blood Pb levels on Ca2+ levels in serum and placenta and placental Ca2+ transfer. Blood samples (maternal and cord) and placental tissue were obtained at birth from 30 women residing in southwest Quebec. Total Ca2+ and Pb levels were measured in maternal and umbilical cord samples and placental tissue at term. The placentas were taken for trophoblast cell isolation and Ca2+ incorporation kinetic experiments. Data showed that Ca2+ in maternal blood did not influence Ca2+ uptake by syncytiotrophoblast. However, although maternal and cord blood Pb levels were low, maternal blood Pb concentration was significantly linked to a decrease in Ca2+ uptake by syncytiotrophoblast. This suggests that exposure to very levels of Pb significantly modifies Ca2+ transfer in syncytiotrophoblasts. Copyright Taylor and Francis Inc.