Avoiding a Swelled Head: Aquaporin‐4 and Brain Edema

Aquaporins are integral membrane proteins that serve as water channels. Aquaporin 4 (AQP4) is an aquaporin specific to the brain. Besides working as the “plumbing system” to allow water to diffuse across the membrane, it also prevents the passage of ions and other solutes. Aquaporin‐4 works in a bundle of four aquaporin monomers to form a tetramer and is highly expressed within astrocytes (cells in the CNS that help maintain homeostasis) and within the blood‐brain barrier. The blood‐brain barrier is a lipophilic membrane which permits lipid penetration freely while preventing water diffusion. Aquaporin‐4 regulates water circulation of the brain and does not require any energy to function, allowing for the simple diffusion of water. AQP4 has been shown to facilitate astrocytic edema and is responsible for the reabsorption of extracellular edema fluid. Symptoms of cerebral edema include nausea, vomiting, Aquaporin‐4 is supposed to maintain the fluid levels through the spinal cord but the real question is how does it do that in the structure it appears to be. Instead of explaining the function of the Aquaporin‐4, we are going to show it through a model we have created. Cerebral edema can occur when a clot is preventing blood access to the brain; the immune system begins to attack and exert fluids via AQP4, resulting in excess fluid. That edema therefore increases pressure within the skull preventing blood from flowing to the brain and occasionally leads to a stroke. If AQP4 can be targeted, then edema can significantly be reduced and become less of a risk to injured brain tissue. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .