BRAIN ELECTROBIOGENESIS PROTECTION INDUCED BY NIMODIPINE AND MK-801 DURING ACUTE-HYPOXIA IN HYPERTENSIVE RATS

The protective effect of nimodipine, a calcium entry blocker, and MK-8 01, an excitatory amino acid antagonist, on the cortical electrobiogen esis of hypertensive SHR-Charles-River adult rats during a 90-s sessio n of acute hypoxia, was tested either with a single treatment or with a therapeutic association. Pretreatment with nimodipine alone (0.1 mg kg(-1), i.v.) was particularly effective in increasing the rat brain r esistence to hypoxia when compared to the controls. MK-801 pretreatmen t alone (3 mg kg(-1), subcutaneous), improved significantly the recove ry of brain electrical activity from hypoxia, as it not only shortened the recovery time but also abolished the post-hypoxic burst activity. The combined pretreatment with both drugs, using the same doses, disp layed a more powerful brain protective effect on the cortical electrob iogenesis than the single drug pretreatment, suggesting the existence of a synergy between nimodipine and MK-801.