31P-MAGNETIC RESONANCE SPECTROSCOPIC STUDY ON THE EFFECT OF GLYCEROL ON COLD-INDUCED BRAIN EDEMA

The aim of the present study was to determine the effects of a hyperos motic agent, 10% glycerol, on both brain energy metabolism and intrace llular pH (pHi) in experimental vasogenic brain edema. Vasogenic brain edema was induced by cold injury applied to bilateral parietal portio ns in 13 mongrel dogs (7 glycerol, 6 control) while, 3 dogs were used as control. Before and at 24 hours after the injury, sequential phosph orous-31 magnetic resonance spectroscopy (P-31-MRS) was performed for 2 hours in order to determine phosphocreatine (PCr), beta-adenosine tr iphosphate (beta-ATP), inorganic phosphate (Pi) levels and pHi. At 24 hours following cold injury, both PCr/Pi and ATP/Pi ratios significant ly decreased from 7.75 to 3.97 and from 2.26 to 1.25, respectively. Fu rthermore, a moderate decrease in pHi of 7.16 to 7.01 was significantl y demonstrated during the same experimental period. Administration of glycerol for 30 minutes significantly increased PCr/Pi from 3.97 to 5. 06 and ATP/Pi from 1.25 to 1.72, respectively. Also, glycerol administ ration caused a significant increase in pHi from 7.01 to 7.11. This st udy indicates that cryogenic injury, in which formation and expansion of vasogenic brain edema a known to occur, results in disturbed brain energy metabolism and in intracellular acidosis; moreover, the adminis tration of glycerol can ameliorate either or both of these derangement s.