Effects of intra-ischemic blood pressure on outcome from 2-vessel occlusion forebrain ischemia in the rat.
Halothane anesthetized Sprague-Dawley rats underwent 10 min of bilateral carotid artery occlusion with mean arterial pressure (MAP) held at 30, 50 or 60 mmHg. Sham rats did not undergo ischemia. A 7-day recovery interval was allowed. Intra-ischemic electroencephalographic (EEG) changes, behavioral function (Days 5-7), and histologic injury (Day 7) were evaluated. Under similar conditions, cerebral blood flow was determined after 10 min ischemia by the [3H]nicotine indicator fractionation technique. EEG isoelectricity was observed in 11 of 11, 5 of 10, and 2 of 11 rats in the 30 mmHg, 50 mmHg, and 60 mmHg groups respectively. Neither passive avoidance cross-over latencies nor general motor scores were affected by intra-ischemic MAP and no differences from sham performance were observed. The per cent of CA1 neurons counted as dead (left and right hemispheres combined) was significantly affected by intra-ischemic MAP (72, 46 and 28% in the 30 mmHg, 50 mmHg, and 60 mmHg groups, respectively; P less than 0.001). A greater than 50% CA1 neuronal mortality rate was present only in those rats exhibiting EEG isoelectricity. However, the number of rats demonstrating greater than a 25% interhemispheric difference in CA1 neuronal loss was greatest in the 50 mmHg group (P less than 0.02). Hippocampal blood flow decreased in association with severity of hypotension (8 +/- 1, 35 +/- 8, and 48 +/- 2 ml/100 g/min (mean +/- S.E.M.) for 30, 50, and 60 mmHg, respectively; P less than 0.01). Again, however, the greatest variability in blood flow was observed at MAP = 50 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)
Gionet
T X
TX
Department of Anesthesia, University of Iowa, Iowa City 52242.
Warner
D S
DS
Verhaegen
M
M
Thomas
J D
JD
Todd
M M
MM
D000818:Animals; D001794:Blood Pressure; D002339:Carotid Arteries; D002540:Cerebral Cortex / Q000502:physiology / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D004569:Electroencephalography; D006624:Hippocampus / Q000502:physiology / Q000503:physiopathology; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D008297:Male; D009043:Motor Activity; D016548:Prosencephalon / Q000502:physiology* / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013997:Time Factors