Cerebral blood flow and glucose metabolism in experimental brain edema

The relationship between cerebral blood flow (CBF) and cerebral metabolic rate of glucose (CMRgl) in the white matter was studied in a plasma infusion model of vasogenic edema in cats. Local CBF, as determined by iodoantipyrine testing, was found to be significantly decreased in edematous white matter (mean +/- standard error of the mean: 17.3 +/- 1.5 ml/100 gm/min) when compared with CBF in the contralateral control white matter (24.8 +/- 1.8 ml/100 gm/min). When the values for edematous brain were corrected for dilution, however, the local CBF averaged 25.3 +/- 1.7 ml/100 gm/min, which was similar to the control value. Local CMRgl was found to be significantly increased in plasma-infused white matter (16.3 +/- 2.2 mumol/100 gm/min) compared with that in control white matter (10.7 +/- 1.3 mumol/100 gm/min). This difference remained, despite correction for dilution and recalculation of local CMRgl values based on altered kinetic constants found in edematous brain. A similar increase in local CMRgl was noted with saline-infusion edema. It is concluded that the increased tissue water level does not alter CBF, but does induce an increase in anaerobic metabolism.