Brain washing Transport of cerebral extracellular fluids and solutes

Regulation of extracellular volume and fluid composition provides a robust microenvironment for brain cells. In peripheral tissue, fluid surplus and solutes are removed from the interstitium via drainage into lymphatic channels. Since the central nervous system lacks a proper lymphatic vasculature, a substantial part of this drainage may occur along paravascular spaces. The aim of the thesis was to investigate the physiology of brain extracellular fluids and their possible role in the removal of solutes from the central nervous system. Using imaging techniques, we revealed a continuous and extensive CSF compartment, in which solutes move, driven by bulk flow and mixing. Furthermore, we suggested that an increased flux of ions and water, associated with hypertension, may play a role in the filtering and accumulation of endogenous waste products in the brain. We also introduced a new and more subtle approach in studying interstitial fluid flow. To conclude, the research presented in this thesis shed light on the physiology and dynamics of extracellular fluids in the brain and has provided directions for future investigations that could reveal the link between hypertension, extracellular fluids and Alzheimer’s disease.