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Systemic ketamine blocks cortical spreading depression but does not delay the onset of terminal anoxic depolarization
J Hernándéz-Cáceres1, R Macias-González, G Brozek
1Instituto de Investigaciones Fundamentales del Cerebro, Academia de Ciencias de Cuba, Havana.
Abstract:
Ketamine (KET)-induced blockade of cortical spreading depression (CSD) was examined in rats (n = 51) anesthetized with pentobarbital (50 mg/kg). CSD was elicited by intracortical injection of 1 microliter of 0.15 mol/l potassium acetate 10-40 min after i.p. injection of 6-50 mg/kg KET. KET was almost ineffective at 6 mg/kg but prevented CSD propagation at 12 mg/kg and at higher dosages. The blockade was maximal 20 min after injection. Terminal anoxic depolarization elicited by N2 breathing developed in control rats after a latency which was not significantly different from that in rats pretreated with 50 and 100 mg/kg KET. The failure of CSD blocking dosages of KET to delay the onset of terminal anoxic depolarization indicates that excitotoxic amino acids play different roles in the mechanism of the anoxia-elicited and CSD-related autoregenerative ionic shifts.