Fig. 5. Effect of HOE642 (HOE), ouabain (Ouab.), catalase (Cat.) and superoxide dismutase (SOD) on hyperthermia-induced phosphorylation of p38-MAPK (A: upper panel). The phosphorylated form of the kinase was detected in extracts (50 µg of protein) from control hearts (0.5 h equilibration followed by 1 h perfusion at 25°C) or hearts perfused after equilibration for 1 h at 42°C in the presence or absence of HOE642 (5 µmol l^–1), ouab (100 µmol l^–1), catalase (150 U ml^–1) and SOD (30 U ml^–1). The effects of HOE642 and ouabain alone were also assessed. As a control for equal protein loading an anti-actin antibody was used (A: bottom panel). Densitometric analysis of phospho-p38-MAPK (B) was performed by laser scanning. (C) Relationship of the net p38-MAPK phosphorylation levels induced by hyperthermia in the presence of the agents assessed to the hyperthermia-induced p38-MAPK phosphorylation levels. 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<0.001 vs control hearts and P<0.001 vs hearts perfused at 42°C.