EFFECT OF OLIGEMIA ON REGIONAL METABOLITE LEVELS IN CAT BRAIN

Abstract

Abstract— Incomplete cerebral ischemia (oligemia) was produced in cat by carotid occlusion combined with arterial hypotension. Lowering arterial pressure to 50–60 Torr for 20 min caused marked alterations of the ATP, phosphocreatine, and lactate content of subcortical white matter. In contrast, metabolite levels in cerebral cortex and caudate nucleus were only moderately perturbed from control values. More severe oligemia resulted when arterial pressure was lowered to 30 Torr for 20 min following carotid occlusion. Metabolite levels in cortex, caudate nucleus, and white matter were greatly altered from control. In the gray matter there was regional heterogeneity of metabolic alteration, as evidenced from the pattern of NADH tissue fluorescence. The cortex contained micro‐patches (0.1mm) of increased NADH, which frequently exhibited a columnar orientation. These findings demonstrate two distinct types of cerebral inhomogeneity of metabolic failure with reduced blood flow; white matter fails before gray matter, and there is micro‐heterogeneity of metabolic failure in the gray matter.