Characteristics of manganese (Mn) transport in rat brain endothelial (RBE4) cells, an in vitro model of the blood–brain barrier

Manganese (Mn), an essential elemental nutrient, is known to be neurotoxic at high occupational levels. We examined the transport of Mn across a monolayer of rat brain endothelial cell (RBE4) to evaluate whether an electromotive permeability mechanism is responsible for Mn transport across the blood–brain barrier (BBB). The 54Mn2+ apparent permeability and flux showed significant temperature-, energy- and pH-dependence, as well as partial sodium-dependence. Additionally, iron (Fe)-rich and Fe-deficient media significantly increased the apparent permeability of 54Mn2+. Finally, Mn flux and permeability decreased when RBE4 cells were grown in astrocyte-conditioned media (ACM), compared to standard alpha-media. These data reinforce observations that transport of Mn across the BBB occurs in part through active transport process.