ALUMINUM-CHLORIDE STIMULATES NACL-DEPENDENT RELEASE OF TAURINE AND GAMMA-AMINOBUTYRIC-ACID IN RAT CORTICAL ASTROCYTES

The release of preloaded radiolabeled taurine (TAU) and gamma-aminobutyric acid (GABA) from cultured rat cortical astrocytes was monitored 15 min before and 30 min after pulse treatment with aluminum chloride, at 5 min intervals. AlCl3 at concentrations ranging from 0.125 to 1 mM stimulated TAU release to 252 and 519%, respectively, in a relatively dose-dependent manner. Release of GABA was not affected by 0.5 mM but was almost doubled by 1 mM AlCl3. The effects of AlCl3 were greatly diminished or abolished when isotonic sucrose was substituted for NaCl in the superfusion media. Interaction of Al3+ ions with membrane transporters of amino acids is suggested to account for their increased release. Possible neurophysiological consequences of the acute effects of aluminum on the neuroactive amino acid transport in astrocytes are discussed.