Fig. 1. Phosphorylation of p38-MAPK by extracellular alkalosis (pH 8.5). (A) Protein (50 µg) from Rana ridibunda hearts perfused without (Co) or with Tris–Tyrode's buffer (pH 8.5) for the times indicated was assessed by immunoblot analysis using a phosphospecific anti-p38-MAPK antibody (top) or total p38-MAPK antibody as a control for equal loading (bottom). Extract from hearts perfused with 0.5 mol l^–1 sorbitol (Sor) for 15 min was used as a positive control. (C) Time course of p38-MAPK phosphorylation induced by reperfusing hearts subjected to extracellular alkalosis (pH 8.5, 2 min; top). Equal loading was assessed by blotting identical samples with an anti-actin-specific antibody (bottom). (B,D) Densitometric analysis of phospho-p38-MAPK bands by laser scanning. Values are means ± s.e.m. for three independent experiments performed with similar findings. *P<0.05, **P<0.01, P<0.001 vs control value.