Aquaporins and brain edema.

Aquaporins are a family of transmembrane proteins that selectively allow the passage of water through the plasma membrane. Their importance is highlighted by their ubiquitous presence from bacteria to mammals. In humans, they are found throughout the body and recent work has highlighted their function within the brain. They are intimately involved in the production of cerebrospinal fluid and the control of water movement at the blood-brain barrier. Aquaporin levels are up-regulated in animal models of trauma, stroke and water intoxication as well as around human malignant brain tumors. They have thus been implicated in the formation of brain edema. Knockout mice, without the aquaporin gene, appear to have reduced brain edema compared to their wild type brethren in models of brain edema. Currently, the clinical treatment of brain edema is limited. Increased knowledge of the aquaporins may open new targeted therapies for brain edema.