Physiological mechanism of water exchange across the blood-brain barrier

Motivation: Studies have shown MRI-measured water exchange across the blood-brain barrier (BBB) can serve as a sensitive biomarker for detecting subtle BBB disruptions. However, physiological mechanisms underlying this water exchange remain unclear. Goal(s): To investigate physiological mechanisms driving water exchange across the BBB. Approach: Vascular exchange imaging (VEXI) was used to measure water exchange across BBB in rats. Ouabain and TGN020 were administered to inhibit Na+, K+-ATPase and AQP4, respectively, to assess their individual contributions to this process. Results: Water exchange across the BBB decreased by 30% after administration of ouabain, but didn't show downward trend after administration of TGN020. Impact: This study advances the understanding of physiological mechanisms regulating water exchange across the BBB and offers a fundamental reference for future research on this topic.