Mechanisms of stimulated taurine release from nervous tissue.

Spontaneous taurine efflux from brain cells is strikingly slow and only moderately enhanced by either homo- or heteroexchange. A part of taurine release evoked by potassium depolarization from brain slices and synaptosomes is clearly calcium dependent when the enhancement of release--to a great extent from glial cells--induced by calcium-free media and calcium chelators is properly taken into account in evaluation. Sodium-free medium is the most effective means in provoking taurine efflux. It is suggested that normally the transmembrane sodium gradients aid in maintaining the high intracellular taurine concentrations.