[Effect of dexamethasone on tumorous brain edema--changes in regional cerebral blood flow and glucose utilization].

An experimental brain tumor was produced by implanting a piece of A.A. ascites tumor into the parietal brain of rat. Local cerebral blood flow (LCBF) and glucose utilization (LCGU) were determined in this model with 14C-iodoantipyrine and 14C-deoxyglucose quantitative autoradiographic methods, respectively, to investigate the change of blood flow and glucose metabolism and the effect of dexamethasone in the brain with tumor. LCBF and LCGU in the peritumoral brain tissue were reduced 75% and 60%, respectively, compared with the values of the control. In the ipsilateral frontal and occipital cortical areas far from the tumor, 50% and 45% reduction of LCBF, respectively, was observed. More than 30% reduction of LCGU was seen in the same areas. In the caudate and corpus callosum ipsilateral to the tumor, LCBF was diminished 25% and 40%, respectively. LCGU was not significantly changed in these areas. No significant changes of LCBF and LCGU were observed in the contralateral hemisphere. In the dexamethasone-treated animal, the reduction of LCBF was less in all areas where it was reduced in the untreated animal. In the peritumoral brain tissue, LCBF was significantly higher compared to that of the untreated group, and 80% of the normal level. In the ipsilateral frontal and occipital cortical areas, caudate and corpus callosum, LCBF was about the same as that of the control group. In the animal treated with dexamethasone, quantitative analysis of LCGU could not be made because of high glucose levels in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)