LOCAL CEREBRAL BLOOD-FLOW DURING THE FIRST HOUR FOLLOWING ACUTE LIGATION OF MULTIPLE ARTERIOLES IN RAT WHISKER BARREL CORTEX

The objectives are to measure the early time-course of the flows of bl ood, red cells, and plasma in brain tissue destined to infarct followi ng arterial occlusion. The flux of fluorescent red blood cells (fRBCs) through venules and the arteriovenous transit times (AVTT) of fluores cein-labeled plasma albumin were periodically monitored in anesthetize d adult Wistar rats before and up to 60 min after permanent ligations of several small branches of the middle cerebral artery. Of note, fRBC is a function of venular erythrocyte flow and volume, whereas AVTT is a function of plasma flow and volume in visible arteriole-capillary-v enule units. In another group of anesthetized rats, local cerebral blo od flow (ICBF) was measured 1 h after permanent arterial occlusion by [C-14]iodoantipyrine (IAP) autoradiography. With this model of focal i schemia, the lesion is highly reproducible and involves part of the wh isker barrel cortex. Infarction of this area was observed in 12 of 13 rats. From 10 to 60 min after arterial occlusion, AVTT was nearly four times longer in the ischemic barrel cortex than at the same site befo re ligations, and fRBC flux was 25%. Neither parameter changed appreci ably over this time. After 60 min of ischemia, ICBF on the ipsilateral barrel cortex was 18% of that on the contralateral side and 15% of th e sham control value for the same area of the barrel cortex. Since who le blood flow in the ischemic barrel cortex was <20% of normal at 60 m in and AVTT and fRBC flux were essentially constant from 10 to 60 min, the rates of plasma and red cell flows were similarly depressed durin g the first hour of arteriolar occlusion. In conclusion, such lowering of red cell, plasma, and blood flows produced consistent infarctions in the barrel cortex. (C) 1998 Academic Press.