Histochemical studies in the zone of ischemia following middle cerebral artery occlusion in cats

Abstract

✓ Representative enzymes in brain were studied by histochemical techniques at intervals varying between 6 hours and 8 weeks after permanent middle cerebral artery occlusion in 18 cats. Unequivocal enzyme changes did not develop until 12 hours after occlusion, and no specific enzyme system was demonstrated to fail prior to others. That the ischemia of the first 6 hours is reversible in the cat was further substantiated by histological studies in a separate group of animals subjected to temporary middle cerebral artery occlusion for 6 hours. This study demonstrated progressive axonal changes, after the period of reversibility, bordering the core area of ischemia and resembling neural tissue reaction to injury in the spinal cord. Correlation of this study with previous biochemical determinations suggests that a self-induced and self-perpetuated toxicity might explain, in part, progressive changes in ischemic areas.