CAPILLARY PATENCY AFTER TRANSIENT MIDDLE CEREBRAL-ARTERY OCCLUSION OF2 H DURATION

Reperfusion after transient focal ischemia of 2 h duration is followed by secondary bioenergetic failure after 4 h of reperfusion. The objec tive of the present study was to explore whether or not this secondary deterioration is due to secondary microcirculatory compromise. Normal fasted rats were subjected to 2 h of MCA occlusion and allowed reperf usion for 2, 4, 6 and 8 h. At predetermined reperfusion times, rats we re injected with Evans blue and decapitated. Capillary patency was det ermined using a fluorescent double-staining technique. No capillary pe rfusion deficits were detected in the ischemic neocortical penumbra, n eocortical focus or striatal focus. We concluded that the secondary de terioration of bioenergetic state is not due to microcirculatory compr omise. Since hyperglycemic animals show pan-necrotic lesions, a hyperg lycemic group was added at 8 h of reperfusion to test if the adverse e ffect of hyperglycemia on ischemic damage is related to capillary comp romise. The results showed that, in hyperglycemic rats, capillary perf usion in the striatal focus was compromised after 8 h of recirculation following 2 h of MCA occlusion. It is concluded that when normoglycem ic rats are subjected to 2 h of MCA occlusion, capillary patency is no t affected during the first 4-6 h of reflow. At 8 h of reflow, though, particularly in hyperglycemic rats, microcirculation is compromised i n the caudoputamenal focus, probably reflecting infarction. (C) 1998 E lsevier Science Ireland Ltd. All rights reserved.