Astrocytes are specialized glial cells found in the brain and spinal cord, they are responsible for maintaining the electrolytic composition of the cerebrospinal fluid, induce the formation of the blood-brain barrier and act as a support and guide for neurons during migration. They keep the ionic composition of the extracellular fluid of the central nervous system through the water channels, Aquaporin-4 (AQP4) and K channels, located in the pedicle processes of the astrocytes in the perivascular space, these cells exchange K and water in said perivascular medium away from the neurons. Astrocytes selectively edematize during hypotonic stress, while neurons do not.
