The present study was designed to examine which type of adenosine receptors was involved in enhancement of high K+-evoked taurine release from in vivo rat hippocampus using microdialysis. Perfusion with 0.5 or 5.0 mM adenosine enhanced high K+-evoked taurine release. Perfusion with 2 μM R(−)-N6-2-phenylisopropyladenosine (PIA), a selective adenosine A1 receptor agonist, did not modulate taurine release. Perfusion with 1 μM 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), a selective adenosine A1 receptor antagonist, increased taurine release. On the other hand, perfusion with 20 μM 2-[4-(2-carboxyethyl)phenethylamino]-5′- N-ethyl-carboxamideadenosine (CGS21680), a selective adenosine A2A receptor agonist, enhanced taurine release, while perfusion with 1 mM 3,7-dimethyl-propagylxanthine (DMPX), an adenosine A2 receptor antagonist, did not affect taurine release. These results demonstrate that adenosine enhances high K+-evoked taurine release via activation of adenosine A2A receptors from both neurons and glial cells of in vivo rat hippocampus. [ABSTRACT FROM AUTHOR]