Local cerebral glucose metabolism in newborn dogs: Effects of hypoxia and halothane anesthesia

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Abstract
Local cerebral glucose utilization (LCGU) was measured in 36 neuroanatomical structures of normal awake, halothane-anesthetized, and hypoxic newborn puppies by the autoradiographic 2-[14C]deoxyglucose method. In normal animals, LCGU was highest in the vestibular nucleus and in other gray matter nuclei of the brainstem and declined in a caudal-to-rostral progression through the neuraxis (i.e., LCGU of cerebellum > thalamus ≅ caudateputamen > cerebral cortex). Lowest rates of glucose metabolism were detected in white matter structures. Halothane anesthesia (1.5% inspired) caused few changes in local glucose metabolism, the most notable being decreased LCGU among structures of the auditory system (cochlear nucleus, lateral lemniscus, inferior colliculus) and increased LCGU in the interpeduncular nucleus. Acute systemic hypoxia (arterial oxygen tension of approximately 12 mm Hg) produced markedly heterogeneous effects on local glucose metabolism: LCGU was increased in some gray matter structures, decreased in the thalamus, and substantially increased in the subcortical white matter and corpus callosum. In puppies whose brains were frozen in situ after 55 minutes of hypoxia, the concentration of lactate was increased ten- to elevenfold in cortical gray and subcortical white matter, but the concentrations of glucose, adenosine triphosphate, and phosphocreatine declined to a greater extent in the white matter. The results suggest that during hypoxia the high rate of glycolysis in white matter exceeded substrate supply so that glucose availability became the limiting factor for local energy production. Such a mechanism may contribute to the white matter injury that often develops following hypoxic-ischemic insults in the perinatal period.