Glycolytic activity and fructose 2, 6-bisphosphate changes in rat brain during ischemia

The brain ischemia of spontaneously hypertensive rat was produced gradually by bilateral ligation of the common carotid arteries. The cortical blood flow was measured with a laser doppler flowmeter before and after ligation of the arteries. At the specified intervals, the brain was frozen in situ with liquid nitrogen. The concentration of blood glucose and glycolytic intermediate in frozen brain were measured and the relationship between glycolytic activity and the concentrations of effectors to PFK-1, such as fructose 2,6-bisphosphate, fructose 1,6-bisphosphate, AMP, ATP, Pi and citrate, was investigated. The changes in glycolytic intermediates, pyridine and adenine nucleotides concentration showed that ischemic change occurred in the brain tissue after 30 min of bilateral ligation of the common carotid arteries, in correlation with the decrease in cortical blood flow. The rate of lactate formation increased during the 30-60 min interval and finally decreased during 60-120 min period of ischemia. This indicates that anaerobic glycolysis was accelerated during the early stages of ischemia. The most potent activator of PFK-1, fructose 2, 6-bisphoshate, increased from 5.3 or 6.7 nmol g during the initial stage of ischemia, and this change preceded the activation of glycolysis and the increase in fructose 1,6-bisphosphate concentration, a result indicated that fructose 2,6-bisphosphate does participate in the activation of glycolysis during brain ischemia in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)