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THE EFFECTS OF HYPERGLYCEMIA ON ISCHEMIC BRAIN EDEMA Shigeki Yura 1 , Kazuhiro Sako 1 , Shizuka Aizawa 1 , Nozomi Suzuki 1 , Yukichi Yonemasu 1 , Mitsuru Kojima 2 1Department of Neurosurgery, Asahikawa Medical College 2Central laboratory for research and education, Asahikawa Medical College pp.571-578
Published Date 1987/6/1
DOI https://doi.org/10.11477/mf.1406205925
  • Abstract
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The effects of hyperglycemia on ischemic brain edema in rats were studied by measuring the local changes in water content of brain and cerebro-vascular permeability using a transient middle cerebral artery (MCA) occlusion model.

Rats, fasted except for water for 12-16 hours, were used. They were anesthetized with halothane and the stem of the left MCA was occluded for 2 hours by a microclip. Reperfusion was performed by removal of the clip. The rats were allowed to awake from anesthesia after removal of the clip. Hyperglycemia was induced by intraperitoneal injection of 50% glucose and same volume of physiological saline was injected intraperitoneally 20 minutes before MCA occlusion in control rats. Cerebrovascular permeability was measured by quantitative autoradiography using 14C-α-amino-isobutyric acid (14C-AIB) 2 hours after reperfusion. The specific gravity of cerebral tissue, determined by the gradient column with bromobenzene and kerosen, was used to study local changes in brain water content 2 hours after MCA occlusion and 2 hours after reperfusion.

In hyperglycemic rats, plasma glucose concent-ration rose to over 500 mg/dl at the peak and then declined. A hyperglycemic state around 300 mg/dl was maintained during the experiments. Elevation of hematocrit and plasma osmolarity were observed in hyperglycemic rats.

At 2 hours after MCA occlusion, specific gravity of the brain was decreased in the left MCA ter-ritory, especially in the frontal cortex, in both groups. The decrease in the frontal cortex in hyperglycemic rats was statistically significant compared with that in the control rats.

At 2 hours after restoration of blood flow fol-lowing 2 hours MCA occlusion, in hyperglycemic rats, the decreases of specific gravities became significant in the entire territory of the left MCA. 14C-AIB autoradiograms disclosed prominent and extensive leakage of the radioactive tracer within the previously ischemic area. This may be inter-preted as that so called "vasogenic edema" was induced by restoration of blood flow in hyper-glycemic rats. On the other hand, in normogly-cemic rats, no demonstrable leakage of the tracer was observed, and specific gravity of the brain revealed a trend to edema resolution.

Ischemic brain edema in early ischemic phase(probably "cytotoxic type") is more prominent in hyperglycemic rats than in normoglycemic rats. Early reperfusion in hyperglycemic rats induces a vasogenic edema, however, it is not observed in normoglycemic rats. Our data suggest the possibi-lity, in hyperglycemia, that reperfusion in acuteischemic phase rather extends postischemic hypo-perfusion area because of the increase of cerebro-vascular resistance and the reduction of perfusion pressure associated with edema development.


Copyright © 1987, Igaku-Shoin Ltd. All rights reserved.

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電子版ISSN 2185-405X 印刷版ISSN 0006-8969 医学書院

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