Blood-brain barrier transport pathways for cytoprotective thiols.

The purpose of this study is to further define transport pathways for biological thiols by blood-brain barrier (BBB) endothelial cells, as a means of identifying endogenous cytoprotective mechanisms and potential therapeutic protocols for oxidative injury. Similar low-affininty, high-capacity passive carriers for glutathione (GSH) were observed at both the luminal (blood-facing) and abluminal (brain-facing) plasma membranes of BBB endothelial cells. These carriers are voltage dependent, favoring outward movement of intact peptide across both membrane domains, including efflux at the luminal plasmalemma where γ-glutamyl transpeptidase is located.