Local cerebral tissue glucose utilization in graded arterial hemorrhagic hypotension, studied by the...

The effect of hemorrhagic arterial hypotension on local cerebral glucose metabolism was studied on 33 rats. The mean arterial pressure was set with the aid of a reservoir at 80, 60, 50 and 40 mmHg pressures. Local cerebral glucose utilization was measured with the 14C-2-D-deoxyglucose accumulation autoradiographic technique. Local glucose consumption decreased somewhat in cortical structures when mean arterial pressure was reduced to 60-50 mmHg. Further decrease in mean arterial pressure to 50-40 mmHg caused inhomogeneity of tissue metabolism. Columns and patches of high glucose consumption interchanged with areas of very low glucose consumption in most telencephalic and cerebellar gray matter structures. Brain stem and white matter structures seem to be less sensitive to decreased mean arterial pressure in the range studied. We found a decrease in glucose utilization rather than an increase with decreasing mean arterial pressure down to 60-50 mmHg (in the range of the autoregulation of cerebral circulation). This finding makes it improbable that autoregulation would be connected with elevated anaerobic metabolism of the tissue. Patchy areas and columns of high glucose consumption found at 50-40 mmHg in all probability reflect areas of increased anaerobic metabolism of glucose. Here, circulation was not enough to transport adequate quantity of oxygen to the tissue, but still it transported relative large amount of glucose. Columns and patches of very low glucose consumption should reflect areas, where circulation was inadequate to transport both enough glucose and oxygen.