Local cerebral glucose utilization in normoxemic and hypoxemic newborn lambs

Abstract

To determine if hypoxemia altered local cerebral glucose utilization (LCGU) in newborn lambs, and where these alterations occurred, we measured LCGU using the 2-[ 14C]deoxyglucose ([ 14C]D-autoradiographic technique in lambs made hypoxemic by gradual reduction in inspired oxygen concentration. In 5 normoxemic control lambs, aged 3 days, LCGU of the cerebral cortex and white matter was higher than published values of LCGU in similar structures in near term normal fetuses and 2–4 times higher than reported values in normoxemic puppies. LCGU was highest in vestibular nuclei and auditory structures, followed by cerebellar nuclei, cerebral subcortical structures, and white matter. In 6 hypoxemic newborn lambs ( p a O 2 14–18 torr) consistent increases in LCGU were noted only in the corona radiata compared to the values obtained in the normoxemic control lambs (36.5 ± 8.1 vs. 23.9 ± 1.7 μmol/100 per min, mean ± S.D., P < 0.02). This increase in LCGU in white matter was clearly noted in autoradiographs in which thin dark central regions within white matter often reached high into the gyri. In the hypoxic group, LCGU of the corona radiata superseded the value in many gray matter structures. In addition, patchy increases of [ 14C]DG utilization were present in the cerebral cortex of two hypoxemic lambs. Acute hypoxemia increases glucose utilization of the corona radiata to values equivalent to many gray matter structures, and leads to heterogeneous glucose metabolism in the cerebral cortex, but does not alter LCGU in other gray matter structures of newborn sheep.