DELAYED TRIPHENYLTETRAZOLIUM CHLORIDE STAINING REMAINS USEFUL FOR EVALUATING CEREBRAL INFARCT VOLUME IN A RAT STROKE MODEL

Sixteen of 24 Sprague-Dawley rats with permanent middle cerebral arter y occlusion for 24 hours were subjected to immediate or 8-hour delayed 2,3,5-triphenyltetrazolium chloride (TTC) staining (n = 8 at each tim e point), the other 8 animals were subjected to immediate or 8-hour de layed measurement of succinate dehydrogenase activity (n = 4 at each t ime point). The TTC staining was of good quality good in all animals, and the infarcted region could be distinguished easily from normal tis sue. There was no significant difference in corrected infarct volume b etween the two groups (263.8 +/- 43.1 versus 264.4 +/- 54.8 mm(3) [mea n +/- standard deviation]). The activity of succinate dehydrogenase wa s not significantly different when normal or infarcted tissue was meas ured immediately after death or with an 8 hour delay, although less ac tivity was detected at both time points in the infarcted tissue. These results demonstrate that an S-hour delay of TTC staining is reliable for evaluating brain infarct volume in a rat stroke model and this pro bably is attributable to the slow deterioration of mitochondrial enzym e activity in nonischemic brain over this time period.