ION CHANNEL INVOLVEMENT IN HYPOXIA-INDUCED SPREADING DEPRESSION IN HIPPOCAMPAL SLICES

Rat hippocampal tissue slices were made hypoxic in control medium and in medium containing the ion channel blockers tetraethylammonium (TEA), 4-aminopyridine (4-AP), or tetrodotoxin (TTX). Postsynaptic evoked potentials, extracellular DC potential V(ec), and in some experiments extracellular potassium concentration [K+]o were monitored in stratum pyramidale of the CA1 region. TEA (10 mM) decreased the latency of hypoxia-induced spreading depression (SD), and reduced the amplitudes of the changes in V(ec) and [K+]o. 4-AP (50-mu-M) also decreased the latency of SD but had no effect on the V(ec) shift. In most slices, TTX (1-mu-M) increased SD latency but had no effect on the V(ec) shift. In some slices, TTX blocked the occurrence of SD.