Influence of Hyperglycemia on Energy Metabolism in Ischemic Brain

The purpose of this study is to investigate e effects of preischemic hyperglycemia on e alterations of'adenosine triphosphate and lactate concentrations in e acutefocal ischernic brain of the cats.

Acute focal cerebral ischemia in cats was induced by occlusion of the left middlecerebral artery through the postorbital technique. The experimental animals were divided into 3 goups: sham control, occlusion and recirculation groups. Each group was divided into 2 subgroups: normoglycemic and hyperglycemic groups.

The experimental results are obtained as fo11ows;

1) In normoglycemic subgroups of occlusion and recirculation proups, amount of adenosinetriphosphate in ischmic brain decreased significantly to 3.0% and 13.0% of the sham control,respectively(p < 0.001).

In hyperglycemic subgroups of occlusion and recirculation groups, amount of adenosine trisphosphate decreased a little more an at in normoglycemic subgroups, even so there wasno statistic significancy(p > 0.1).

2) In normoglycemic subgroups of occlusion and recirculation groups, amount of lactate inischemic brain increased signigicantly to 175.7% and 187.9% of the sham control, respectively(p < 0.001).

In hyperglycemic subgroups of occlusion and recirculation groups, amount of lactate increased nore than that in normoglycemic subgroups with statistic significancy(0.001 < p < 0.01).

These results suggest that hyperglycemia before ischemia serves to elevate glucose transport into brain tissue and thereby, to promote profound tissue acidosis throughanaerobic glycolysis caused by a failure of adenosine triphosphate stnthesis during the ischemicperiod.