Fig. 2. Time profile of hyperthermia (42°C)-induced p38-MAPK (A) and Hsp27 (C) phosphorylation in samples from isolated perfused Rana ridibunda hearts. (A) Upper panel: phospho-p38-MAPK was detected in extracts (50 µg of protein) from control hearts (0.5 h equilibration at 25°C followed by 0.5 h perfusion at 25°C) or hearts perfused after equilibration at 42°C for increasing periods of time as indicated. (C) Upper panel: phospho-Hsp27 was detected in corresponding samples. As a control for equal protein loading, an anti-actin antibody was used (A,C: bottom panels). Densitometric analysis of phospho-p38 (B) and phospho-Hsp27 (D) bands was performed by laser scanning. Western blots shown are representative of at least three independent experiments while data are means ± s.e.m. from at least three independent experiments. ^*P<0.05 and ^**P<0.01 vs control (untreated) hearts.