Microsphere analysis of local cerebral and extracerebral blood flow after complete ischemia of the cat brain for one hour.

In normothermic anesthetized cats complete cerebral circulatory arrest for one h was produced and followed by blood recirculation of the brain for 30 min to 4 h. Total and local blood flow of the brain, kidney, heart and liver were measured before and after ischemia using radioactive labelled microspheres. Before ischemia blood flow of the brain was 39.1 +/- 2.3 ml/100 g/min, of the kidney 307.2 +/- 28.3 ml/100 g/min, of the heart 241.1 +/- 32.5 ml/100 g/mmin and of the liver 87.8 +/- 25.6 ml/100 g/min (means +/- SEM). Regional flow rates within the brain varied between 35 and 51 ml/100 g/min. Reactive hyperemia was present in the brain 30 min after the beginning of recirculation following ischemia for 1 h. Local cerebral flow rates increased three to five times above the control flow, depending on the respective region. Mean cerebral blood flow returned to or slightly below normal, 2 to 4 h after ischemia, but there was considerable redistribution of flow rates within the brain. The filter capacity of the brain for microspheres of 15 mu and 50 mu diameter did not change after ischemia indicating that postischemic blood recirculation was not accompanied by an opening of arteriovenous shunts.