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Impaired cerebral autoregulation 24 h after induction of transient unilateral focal ischaemia in the rat
Author(s) -
MacGregor D. G.,
Carswell H. V. O.,
Graham D. I.,
McCulloch J.,
Macrae I. M.
Publication year - 2000
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2000.00880.x
Subject(s) - autoregulation , cerebral blood flow , middle cerebral artery , anesthesia , medicine , cerebral autoregulation , cerebral cortex , ischemia , white matter , cortex (anatomy) , cardiology , blood pressure , magnetic resonance imaging , neuroscience , psychology , radiology
Cerebral blood flow (CBF) and cerebral autoregulation have been investigated 24 h after transient focal ischaemia in the rat. Cerebral blood flow was measured autoradiographically before and during a moderate hypotensive challenge, to test autoregulatory responses, using two CBF tracers, 99m Tc‐d,l‐hexamethylproyleneamine oxide and 14 C‐iodoantipyrine. Prior to induced hypotension, CBF was significantly reduced within areas of infarction; cortex (28 ± 20 compared with 109 ± 23 mL/100 g/min contralateral to ischaemic focus, P = 0.001) and caudate (57 ± 31 compared with 141 ± 32 mL/100 g/min contralaterally, P = 0.005). The hypotensive challenge (mean arterial pressure reduced to 60 mmHg by increasing halothane concentration) did not compromise grey matter autoregulation in the contralateral hemisphere; CBF data were not significantly different at normotension and during hypotension. However, in the ipsilateral hemisphere, a significant volume of cortex adjacent to the infarct, which exhibited normal flow at normotension, became oligaemic during the hypotensive challenge (e.g. frontal parietal cortex 109 ± 15% to 65 ± 15% of cerebellar flow, P < 0.01). This resulted in a 2.5‐fold increase in the volume of cortex which fell below 50% cerebellar flow (39 ± 34 to 97 ± 46 mm 3 , P = 0.003). Moderate hypotension induced a significant reduction in CBF in both ipsilateral and contralateral subcortical white matter (P < 0.01). In peri‐infarct caudate tissue, CBF was not significantly affected by hypotension. In conclusion, a significant volume of histologically normal cortex within the middle cerebral artery territory was found to have essentially normal levels of CBF but impaired autoregulatory function at 24 h post‐ischaemia.