The evolution of focal ischemic damage: a metabolic analysis.

Focal cerebral ischemia in the rat was induced by left middle cerebral artery occlusion. The area of ischemia was determined by infusion of a qualitative perfusion indicator, neutral red. The temporal evolution of alterations in regional energy metabolism was assessed by direct microquantitative histochemical analysis of high-energy phosphates, glucose, glycogen, and lactate content of the tissue. Perfusion analyses demonstrated a perifocal region of diminished, but not absent perfusion up to 6 hr after occlusion. By 24 hr, there was an abrupt demarcation between perfused and nonperfused regions. Profound metabolic alterations were seen as early as 20 min after occlusion. Although there was an area of intermediate metabolic derangement in the more medial portions of the lateral ipsilateral cortex up to 6 hr, by 24 hr there was an abrupt transition from normal to abnormal cortex. No evidence of metabolic recovery was seen in this model of permanent occlusion.