Dexamethasone enhances calcium-activated potassium channel expression in blood-brain tumor barrier in a rat brain tumor model

This study was performed to determine whether dexamethasone (DEX) had an effect on calcium-activated potassium channels (KCa channels) in blood-brain tumor barrier (BTB). Using a rat brain glioma model, we found that the expression of KCa channels protein was significantly increased in brain tumor tissue. And bradykinin-induced increase of KCa channels protein was further enhanced after DEX pretreatment for 3 days. In addition, DEX pretreatment enhanced bradykinin-mediated up-regulation of the density of IKCa in the rat brain C6 cells in vitro BTB. Bradykinin markedly increased BTB permeability independent of DEX pretreatment. All of these results strongly suggest that DEX could regulate the target in the transcellular pathway of BTB-KCa channels.