A Comparison of Local Rates of Glucose Utilization in Spinal Cord and Brain in Conscious and Nitrous Oxide- or Pentobarbital-treated Rats

Abstract

Local rates of glucose utilization in the spinal cord and brain were measured with the 2-[14C]deoxyglucose method in conscious and in paralyzed and mechanically ventilated pentobarbital- or 70% nitrous oxide-treated rats. In conscious animal lumbar spinal cord glucose utilization is only 40–50% that of the cerebral cortex and shows little laminar heterogeneity. Pentobarbital reduces and nitrous oxide increases the cerebral glucose utilization of most structures. The effect of paralysis and nitrous oxide analgesia on lumbar spinal cord glucose utilization is quantitatively similar to that produced in brain; 15–25% increases occur in most spinal cord laminae and cerebral structures. In contrast, the 10–20% reduction in spinal cord gray matter metabolism in the paralyzed and pentobarbital-treated animals is considerably less than the 20–50% depression measured in most brain structures. From these data the authors conclude that, relative to that of most cerebral structures, spinal cord metabolism is less sensitive to depression by barbiturates and suggest that differences in the cell populations of these tissues may account partially for this observation.