Cerebral metabolic responses of hyperglycemic immature rats to hypoxia-ischemia.
Unlike adult rats, glucose supplementation of immature rats does not lead to accentuated hypoxic-ischemic brain damage. To explore the reason for this age-specific paradox, we subjected 7-day postnatal rats to unilateral common carotid artery occlusion followed by a subcutaneous injection of either 0.1 ml 50% glucose or normal saline. They were then exposed to hypoxia with 8% oxygen, during which they received 2.5 microCi 2-[14C]-glucose or were quick-frozen for brain metabolite analysis. During hypoxia-ischemia, glucose transport into the ipsilateral cerebral hemisphere of the hyperglycemic rats was greater (+100-150%) than in normoglycemic animals. However, glucose consumption was similar in the two groups. Glucose concentrations in brain were lower during hypoxia-ischemia in the normoglycemic animals, whereas lactate increased to similar levels in the two groups. The high-energy phosphate reserves, ATP and phosphocreatine, were depleted to a similar extent. Thus, hyperglycemia combined with hypoxia-ischemia, although associated with increased glucose transport into brain, does not lead to enhanced glucose utilization or lactate accumulation by brain over that of hypoxia-ischemia alone.
D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000150:complications / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D006943:Hyperglycemia / Q000150:complications / Q000378:metabolism*; D002534:Hypoxia, Brain / Q000150:complications / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D010725:Phosphocreatine / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D051381:Rats; D011919:Rats, Inbred Strains
D000227:Adenine Nucleotides; D001786:Blood Glucose; D007773:Lactates; D011773:Pyruvates; D010725:Phosphocreatine; D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose