Cortical ischemia: effect upon direct cortical response.
Correlation of cortical blood flow as measured by a thermal diffusion flow probe (CBFp) with the direct cortical response (DCR) was studied in 48 lightly anesthetized cats with global ischemia. Thresholds for attenuation and loss of DCR were 21.3 +/- 4.7 and 8.7 and 3.4 ml/100 g/min respectively. In abrupt ischemia, CBFp of 0-3 ml/100 g/min produced absence of DCR in 6 min or less; however, at CBFp of 5-10 ml/100 g/min, the time to obliteration of DCR varied from 5 to 180 min. DCR was unlikely to recover after 13 min of 0-2 ml/100 g/min and after 35 min of 4-5 ml/100 g/min. At higher flows, DCR could recover over 60 min or more of ischemia. With gradual production of ischemia, flows less than 20 ml/100 g/min for over 60 min had a detrimental effect upon recovery of DCR if DCR was lost for 7.5 min or more. Some evidence that implied adaptability of the cortex to ischemia was found.
D000818:Animals; D001157:Arterial Occlusive Diseases / Q000209:etiology / Q000503:physiopathology; D016122:Brachiocephalic Trunk / Q000503:physiopathology; D002545:Brain Ischemia / Q000209:etiology / Q000503:physiopathology*; D002415:Cats; D002540:Cerebral Cortex / Q000098:blood supply*; D004558:Electric Stimulation; D005260:Female; D008297:Male; D013348:Subclavian Artery / Q000503:physiopathology