[Distribution and constitutional changes of edema fluid in cytotoxic brain edema analyzed by electron microscopy and differential scanning calorimetry].

To understand the pathogenesis of brain edema, we studied distribution and constitutional changes of brain-tissue water by morphological and thermoanalytical methods in cytotoxic brain edema induced by 6-aminonicotinamide (6-ANA). Ninety-two Wistar rats were divided into three groups; Group I rats receiving physiological salt solution intraperitoneally served as controls. Group II and III animals were intraperitoneally given 120 mg/kg and 36 mg/kg of 6-ANA respectively. All animals were starved after injection of drugs to exclude differences in water intake. Then they were decapitated at 3, 6, 12, 24, 36 or 48 hours to measure specific gravity (SG) of large brain tissue (1.1-1.5 g), and to evaluate water content (WC) and free water ratio (FWR) of small brain-tissue samples (15-35 mg) taken from the frontal cortex; WC was measured by a drying-weighing method, and FWR was analyzed with a differential scanning calorimeter. Moreover morphological changes of the frontal cortex of the brain were studied in Group II (n = 12) at 3, 6, 12, 24 and 48 hours with an electron microscope. Neurological status of animals administered 6-ANA (Group II and III) deteriorated with time. Morphological studies showed that perivascular astrocytes and astrocytic processes in the cerebral cortex were swollen most remarkably at 48 hours. However neuronal and endothelial cells were almost intact. The FWR of Group I decreased significantly about four per cent (p less than 0.001) after being starved for 48 hours. But the SG and WC of the group showed little change.(ABSTRACT TRUNCATED AT 250 WORDS)