Decreased blood volume with hypoperfusion during recovery from total cerebral ischaemia in dogs.

Reversible, total cerebral ischaemia of eight minutes duration was produced in a closed-chest dog model. Before, and at intervals after, this insult regional cerebral blood flow was determined by radiolabelled microsphere injection; and cerebral cortical capillary mean transit time was determined by reflection spectrophotometry. From these two measured parameters, cerebral cortical blood volume was calculated. After one hour of reperfusion following eight minutes of total cerebral ischaemia; cerebral blood flow was half of pre-ischaemic blood flow and mean transit time was increased by half. These results indicate that the delayed hypoperfusion following total cerebral ischaemia is accompanied by a decreased cerebral cortical blood volume mediated by vasoconstriction.