Biochemical changes during graded brain ischemia in gerbils. Part 2. Regional evaluation of cerebral blood flow and brain metabolites.

Regional changes of cerebral blood flow and biochemical substrates were assessed in the gerbil brain following different grades of cerebral ischemia. Ischemia was produced by occlusion of the right common carotid and left external carotid arteries. Gerbils were classified according to the severity of neurological symptoms as animals without, with mild and with severe neurological deficits. Brains were frozen in situ, sliced in 20-microns sections and processed for pictorial presentation of glucose and ATP, using bioluminescence techniques. Cerebral blood flow was determined in adjacent brain sections, using [14C]iodoantipyrine autoradiography. NADH fluorescence was recorded by illuminating the surface of the tissue block with ultraviolet light. Most animals without visible neurological symptoms exhibited reduced blood flow in circumscribed regions of cortex and basal ganglia of the right hemisphere without concomitant changes of biochemical substrates. In animals with mild neurological symptoms, blood flow in the right hemisphere was reduced, glucose and ATP decreased, and NADH fluorescence unhomogeneously enhanced. In animals with severe neurological symptoms blood flow was almost arrested in the right hemisphere and was distinctly reduced in the medial parts of the left hemisphere. The ischemic tissue was depleted from glucose and ATP, and exhibited bright NADH fluorescence. The severity of neurological symptoms, in consequence, correlated closely with both the degree and the size of biochemical lesions observed in the ischemic territory.