[Cerebral blood flow in rabbits during hypoperfusion of the brain. Flow distribution and methodological problems...

Brains of rabbits were perfused by arterial blood via the internal carotids after ligation of vertebral and external carotid arteries. The effect of the reduction of cerebral perfusion volume on cerebral blood flow was studied by recording the clearance of Krypton-85 from the brains. The clearance curves obtained by recording the gamma radiation of the Krypton-85 represented the sum of tissue clearances from the whole brain (about 10 g) and about 45 g of extracerebral tissue and so were not representative of cerebral or cortical bloow flow. Using external beta-counting the cortical blood flows calculated from the tissue-clearance curves reached mean values of 87 and 159 ml/100 g/min in perfusions with 12 and 18 ml/min respectively. But during reduced cerebral perfusion (2 ml/min) the clearance curves gave cortical blood flow values of 56 ml/100 g/min on the average and so exceeded the values calculated from the perfusion volume (2 ml/min) and the brain-weight (10 g) two to three times. It is concluded that regions of nonperfusion exceeding 50% of the cerebral tissue coexisted with adequately perfused areas. In hypoperfusion the cortical metabolic state was sufficiently correlated with the perfusion volume, but no correlation existed with the cortical blood flow calculated from the clearance curves.