Correlation between Periinfaret Cortical Spreading depression and Ischemic Volume in Rats

ABSTRACT

Cortical spreading Depression(CSD) is a transient depression of neuronal activity that spreads across the cortical surface and is associated with profound changes in blood flow, extracellular ion concentration. Direct Current(DC) potentials and cell membrane potentials. One of the electrophysiological disturbance in the periinfarct surrounding is spontaneous occurrence of repeated CSD like DC shifts associated with increased energy demand. Due to restricted blood flow to the periinfarct border zone, elevated metabolic demand is potentially hazardous. So the authors designed this experiment to verify the correlation between periinfarct cortical spreading depression and ischemic volume following permanent middle cerebral artery(MCA) occlusion in rats. Sprague-Dawley rats(n=27) were anesthetized with 0.5~1% halothane, and artificially ventilated through a tracheal cannula. Arterial pressure, blood gases and body temperature were controlled. The middle cerebral artery(MCA) was occluded distally to the lenticulostriate branches. Measurements of CSD activity were made for 4 hours in each animal infarct volume was determined 6 hours later in 2,3,5-triphenyl tetrazolium chloride(TTC)- stained section. For 4 hours after MCA occlusion, the CSDs were found in all experimental animals with a range of 2~9 times. Those CSDs were of varying duration "small"(1min) SDs and mean of total duration of SD was 10.5+/-10.3 min during 4 hours of MCA occlusion. Neuropathological evaluation of brain infarct in the rats, which had been allowed to survive for 6 hours after MCA occlusion showed a mean volume of 89.7+/-45.3 mm3. Serial observation of duration of CSD prologation of duration of CSD nor the frequency of CSD in the penumbral zone correlated with the volume of infarct.However total duration of CSD was slightly related with the infarct volume after 6 hours of the permanent MCA occlusion(r=0.414, p=0.0318) .