Fig. 4. Profile of caspase 3 and poly(ADP-ribose) polymerase (PARP) cleavage in samples from isolated Rana ridibunda hearts perfused after equilibration at 42°C for increasing periods of time as indicated. (A) Upper panel: pro-caspase 3 immunoreactivity was observed with no cleaved active forms of caspase 3 detected. (B) Upper panel: proteolytic processing of PARP was observed and quantification of its fragment was performed by laser scanning densitometry (C). The membranes were re-probed with an anti-actin antibody so as to verify equal protein loading (A,B: bottom panels). Western blots shown are representative of at least three independent experiments while data are means ± s.e.m. for at least three independent experiments. ^*P<0.05 and P<0.001 vs control hearts (0.5 h equilibration followed by 1 h perfusion at 25°C).