Effects of hypoglycemia and diabetes on fuel metabolism by rat brain microvessels.
Glucose and beta-hydroxybutyrate metabolism were compared in isolated cerebral microvessels from chronically diabetic and hypoglycemic rats. As noted previously, glucose oxidation and conversion to lactate are diminished in rats with streptozotocin-induced diabetes. The decrease in glucose metabolism did not result from selective damage to diabetic vessels during isolation, since the ATP level and the ATP/ADP ratio were similar to those of nondiabetic rats, and O2 consumption was increased. In addition, cerebral microvessel oxidation of beta-hydroxybutyrate was enhanced by diabetes. By contrast, microvessels from rats made chronically hypoglycemic by insulinoma engrafting 30 days earlier had a more than twofold increase in glucose oxidation and conversion to lactate, whereas their oxidation of beta-hydroxybutyrate was diminished by 50%. Unlike the insulinoma rats, no consistent increase in glucose metabolism was observed in microvessels from rats made hypoglycemic either by acute insulin administration or by a 4-day infusion of insulin. These results indicate that diabetes, and under some circumstances chronic hypoglycemia, markedly alters fuel metabolism in the cerebral microvasculature.
McCall
A L
AL
Evans Memorial Department of Medicine, Boston University School of Medicine, Massachusetts.
Sussman
I
I
Tornheim
K
K
Cordero
R
R
Ruderman
N B
NB
D020155:3-Hydroxybutyric Acid; D000818:Animals; D002196:Capillaries / Q000378:metabolism; D002560:Cerebrovascular Circulation; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004734:Energy Metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D006885:Hydroxybutyrates / Q000378:metabolism; D007003:Hypoglycemia / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D007340:Insulinoma; D008297:Male; D009368:Neoplasm Transplantation; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D013311:Streptozocin
D006885:Hydroxybutyrates; D007328:Insulin; D013311:Streptozocin; D005947:Glucose; D020155:3-Hydroxybutyric Acid