Fig. 5. (A) Extracts (100 µg of protein) from hearts perfused with an alkaline (pH 8.5) Tris–Tyrode's perfusion buffer for the indicated times were assayed for MAPKAPK2 phosphorylation through immunoblot analysis using an antibody specific for the phosphorylated form of MAPKAPK2 (top). Samples from hearts perfused with 0.5 mol l^–1 sorbitol (Sor) for 15 min were used as positive control. Equal loading was assessed in identical samples using an antibody against total MAPKAPK2 (bottom). (B) Densitometric analysis of phospho-MAPKAPK2 bands by laser scanning. Results are means ± s.e.m. for three independent experiments. *P<0.05, **P<0.01 vs control value.