ADENOSINE TRANSPORT INHIBITORS ENHANCE HIGH K-EVOKED TAURINE RELEASE FROM RAT HIPPOCAMPUS()

We examined the effects of Ca2+-free medium containing 20 mM Mg2+, a n on-selective adenosine receptor antagonist, theophylline, and adenosin e transport inhibitors, dipyridamole and nitrobenzylthioinosine, on hi gh K+-evoked spreading depression glutamate, and taurine release from the rat hippocampus using brain microdialysis. High K+ alone perfusion evoked spreading depression and increased glutamate release followed by taurine efflux. Perfusion of Ca2(+)-free medium with high K+ never evoked spreading depression and decreased the high K+-evoked taurine r elease. Perfusion of theophylline (1 mM) increased the occurrence of h igh K+-evoked spreading depression and glutamate release, but did not modify taurine release. In contrast, simultaneous perfusion of dipyrid amole (100 mu M) and nitrobenzylthioinosine (50 mu M) reduced the occu rrence of spreading depression and the high K+-evoked glutamate releas e, but enhanced significantly the taurine efflux. These findings sugge st that endogenous taurine with adenosine may have neuroprotective act ions against high K+-evoked glutamate release and spreading depression in the rat hippocampus, in addition to its osmoregulatory action.