Haemodynamic changes in pre and post ischaemia following simulated embolic stroke of middle cerebral artery occlusion.
The effects of middle cerebral artery (MCA) occlusion (15, 30, 60 min) and recirculation of cerebral blood flow (CBF) were studied in 18 rabbits. The change of cortical oxygen tension (CoPo2) accompanying MCA occlusion was also recorded in 12 rabbits and was compared with the results of CBF recording. CBF and CoPo2 immediately decreased to a minimal level following MCA occlusion and partially improved in the first 5 min of occlusion. CBF and CoPo2 values in the first 5 min following occlusion were significantly higher than the minimal values. The degree of CBF and CoPo2 recovery in the first 5 min of occlusion had a statistically significant correlation with the minimal values. It was postulated that local tissue acidosis due to ischaemia was responsible for this recovery in the early occlusive phase. CBF and CoPo2 became relatively stable after 5 min of occlusion. The results suggest that following embolic occlusion, the degree of recovery of CBF following its initial depression is one of the pathophysiological mechanisms that differentiate between TIAs and stroke. Postischaemic hyperperfusion was observed in all cases after 15 to 60 min of occlusion. The duration of postischaemic hyperperfusion did not correlate with the CBF value just before reperfusion. However, the magnitude of postischaemic hyperperfusion had a significant correlation with the depression of the CBF value just before reperfusion. It could be concluded from our results that the magnitude of postischaemic hyperperfusion represented the severity of ischaemia, at least up to 60 min of occlusion.
Kaminogo
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D000818:Animals; D002545:Brain Ischemia / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000032:analysis / Q000098:blood supply; D002560:Cerebrovascular Circulation; D005260:Female; D006439:Hemodynamics; D002542:Intracranial Embolism and Thrombosis / Q000503:physiopathology*; D002546:Ischemic Attack, Transient / Q000503:physiopathology; D008297:Male; D010100:Oxygen / Q000032:analysis; D011817:Rabbits; D013997:Time Factors; D014655:Vascular Resistance
D010100:Oxygen