Drs. Yokel and Crossgrove at the University of Kentucky Medical Center studied the mechanisms by which manganese enters and leaves the brain across the blood–brain barrier and, in particular, whether transporter molecules are involved. The investigators used in vivo brain perfusion in rats as well as in vitro tests in several cell lines to assess specific characteristics of manganese transport, such as pH and energy dependence. Manganese transport rates were compared with those of sucrose and dextran, which do not easily cross the blood–brain barrier. Experiments to identify putative transporters focused on known transporter molecules, such as a divalent metal transporter, a monocarboxylate transporter, and calcium channels.