A possible role for taurine in osmoregulation within the brain.

Intracranial microdialysis was used to measure changes in extracellular amino acids within the rat brain during local osmotic alteration of the extracellular microenvironment or during systemic water intoxication. Increased cellular hydration produced by either of these methods was accompanied by a marked increase in extracellular taurine levels without affecting the other amino acids measured. With local osmotic alteration, this increase was osmolarity dependent and reversible. The specificity, sensitivity, and reversibility of the increase in extracellular taurine strongly suggest a functional role in osmoregulation in the brain under normal as well as pathological conditions.