Propidium iodide compares favorably with histology and triphenyl tetrazolium chloride in the assessment of experimentally-induced infarct size

Quantitative assessment of infarct size after histology processing or by te trazolium staining requires long reperfusion times to facilitate the deline ation of the injured tissue. We evaluated the nucleic acid stain propidium iodide as an alternate technique for assessment of infarct size because it does not require extended reperfusion and is accomplished with more simple tissue processing. Eight mice underwent 45 min of coronary artery occlusion and 24 h of reperf usion, after which propidium iodide was administered and allowed to circula te for 15 min. Hearts were excised, sliced into transverse slices approxima tely 620 mu m thick, and photographed for determination of infarction with propidium iodide. Slices were processed by standard histology techniques, a nd infarction was evaluated using classical criteria of necrosis. In four o ther mice, infarct size was assessed by both triphenyl tetrazolium chloride and propidium iodide staining. A total of 46 slices were analysed and infa rction was described as a percentage of the cross-sectional area of the sli ce. The correlation (r = 0.94), orthogonal regression line (y = 0.9x + 1.8), an d the percentage of the cross-section infarcted (histology 17.5 +/- 3.0% v propidium iodide 18.5 +/- 3.0%), demonstrates that infarct size assessment after propidium iodide staining or histology processing yields the same res ults. Similarly, propidium iodide measurement of infarct size was comparabl e to that obtained with TCC staining (22.5 +/- 4.1%, v 25.4 +/- 5.4%, respe ctively, r = 0.84). We conclude that propidium iodide staining yields accur ate infarct size assessment and is a simpler alternative to tetrazolium sta ining or histologic processing. (C) 2000 Academic Press.