Effects of a broad-spectrum caspase inhibitor and volume-regulatory Cl− channel inhibitors on cell viability and membrane integrity. (A) Global warm I/R stress-induced TTC-unstained areas in the 24-hr-reperfused hearts (warm I/R [24 hr]). Z-Asp-DCB (B), DIDS (C), or NPPB (D) significantly decreased the TTC-unstained areas (original magnification ×1). (E) The percentage of the TTC-unstained area versus the total left ventricle area. The inhibitors significantly reduced the TTC-unstained area. *P <0.005 vs. warm I/R (24 hr) group. (F–H) HRP infiltration assaying, TTC staining, and TUNEL staining were performed simultaneously on the same frozen section (10-μm thick; original magnification ×400). HRP was administered intravenously to recipient rats to assess the membrane rupture or permeability of myocytes. (F) TTC-positive areas, which are HRP- and TUNEL-negative. Reddish snowy-crystalline bodies can be seen in the TTC-stained cytoplasm (arrows). (G) TUNEL-positive myocytes (brown-colored nuclei, arrowheads), which are slightly HRP-positive and TTC-negative. The HRP-positive signal is green in color in the cytoplasm of myocytes. (H) Strongly HRP-positive myocytes, which are TUNEL- and TTC-negative.