COLLATERAL HEMODYNAMICS AFTER MIDDLE CEREBRAL-ARTERY OCCLUSION IN WISTAR AND FISCHER-344 RATS

We investigated whether the difference in infarction volume after occl usion of a long proximal segment of the middle cerebral artery between Wistar and Fischer-344 rats, is caused by differences in collateral b lood flow rate through leptomeningeal anastomoses. In view of the retr ograde direction of collateral blood flow into the middle cerebral art ery territory, we developed parasagittal laser-Doppler flowmetry. Usin g this method two laser-Doppler probes are placed on the cerebral cort ex: probe 1 is placed near the anastomoses between the middle- and ant erior cerebral artery, probe 2 is placed 2 mm further away from these anastomoses than probe 1. We found in both rat strains a comparable re lation between the areas under the curve of the signal measured by bot h laser-Doppler probes for 2 h after middle cerebral artery occlusion. This relation is considered to be a measurement of the collateral blo od flow rate into the middle cerebral artery territory through leptome ningeal anastomoses after middle cerebral artery occlusion. We conclud e that collateral blood flow for the two strains were essentially simi lar for the initial 2 h after MCA occlusion. Although these collateral blood flows could have been different at a later time, it is unlikely that the interstrain difference in cerebral infarction volume between Wistar and Fischer-344 rats after proximal middle cerebral artery occ lusion is caused by an apparent interstrain difference in the magnitud e of collateral blood flow rate through leptomeningeal anastomoses. Th e parasagittal laser-Doppler flowmetry technique we developed for thes e experiments is currently successfully used in our laboratory to eval uate the efficacy of hemodynamically active pharmacotherapeutical agen ts in raising the collateral blood flow rate into the middle cerebral artery territory after middle cerebral artery occlusion. (C) 1998 Else vier Science B.V. All rights reserved.