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Effect of hemodilution on regional cerebral blood flow during chronic hyperglycemia in rats
1Department of Medicine (Division of Neurology), Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Regional cerebral blood flow decreases during chronic hyperglycemia, a condition frequently associated with elevated hematocrit. To test the hypothesis that an elevated hematocrit is responsible for the reduced regional cerebral blood flow during chronic hyperglycemia, I used isovolemic hemodilution to normalize the hematocrit in seven normoglycemic and seven streptozotocin-treated (hyperglycemic) rats. Regional cerebral blood flow was measured in 28 awake, restrained rats (14 normoglycemic and 14 hyperglycemic) using [14C]iodoantipyrine and dissection of 17 brain regions. Hemodilution lowered the hematocrit by 6 units (13%) and increased the average cerebral blood flow by 14%. Chronic hyperglycemia did not elevate the hematocrit, but it decreased the average cerebral blood flow by 12% and that in nine nontelencephalic brain regions by 17%. This effect was independent of changes in hematocrit caused by hemodilution. The reduced regional cerebral blood flow during chronic hyperglycemia is not caused by elevated hematocrit.
Regional cerebral blood flow decreases during chronic hyperglycemia, a condition frequently associated with elevated hematocrit. To test the hypothesis that an elevated hematocrit is responsible for the reduced regional cerebral blood flow during chronic hyperglycemia, I used isovolemic hemodilution to normalize the hematocrit in seven normoglycemic and seven streptozotocin-treated (hyperglycemic) rats. Regional cerebral blood flow was measured in 28 awake, restrained rats (14 normoglycemic and 14 hyperglycemic) using [14C]iodoantipyrine and dissection of 17 brain regions. Hemodilution lowered the hematocrit by 6 units (13%) and increased the average cerebral blood flow by 14%. Chronic hyperglycemia did not elevate the hematocrit, but it decreased the average cerebral blood flow by 12% and that in nine nontelencephalic brain regions by 17%. This effect was independent of changes in hematocrit caused by hemodilution. The reduced regional cerebral blood flow during chronic hyperglycemia is not caused by elevated hematocrit.