[Sequential changes of autoregulation in experimental focal cerebral ischemia--pathophysiology at the center, periphery and outside of the focal cerebral ischemia].

In order to elucidate the relationship between the degree of autoregulatory loss and the intensity or the duration of ischemia, and the difference of locations in and around the ischemic focus, we used the canine thalamic infarction model and studied the sequential changes of rCBF and autoregulation during 6 hours following vascular occlusion. The value of rCBF was measured by the hydrogen clearance method and autoregulation was tested by raising the blood pressure with drip infusion of angiotensin II. In the center of ischemic focus, autoregulation was impaired after 1, 3 and 5 hours following occlusion in the animals with moderate ischemia. In the animals with mild and severe ischemia, autoregulation was preserved during occlusion, but in the latter we thought it false autoregulation. In the periphery of infarctic focus with severe ischemia, autoregulation was impaired after 3 and 5 hours following occlusion. Outside of the infarctic focus with severe ischemia, autoregulation was preserved during occlusion, but in 2 of 6 animals rCBF decreased despite of raising blood pressure and it was thought to be paradoxical response.