Fig. 5. Time course of the effect of thermal stress upon p38-MAPK phosphorylation in the amphibian heart. Phosphorylated p38-MAPK was detected in extracts (100 µg of protein) from control hearts perfused at 25°C (C), hearts perfused with 0.5 mol l–1 sorbitol for 15 min at 25°C (S), or hearts perfused at 15°C (Ai) or 42°C (Aii) for the indicated times. (Aiii) Total p38-MAPK levels detected in samples from control hearts perfused at 25°C (C) or hearts perfused at 42°C for the indicated times, as a µcontrol for loading. The western blots shown are representative of three independent experiments. Molecular mass markers (kDa) are shown to the right. (B,C) Densitometric analysis of phospho-p38-MAPK bands by laser scanning. Values are means ± S.E.M. for three independent experiments performed with similar results. Values significantly different from controls are indicated; *P<0.05, **P<0.01, 
P<0.001.
