Fig. 2. Effect of the specific inhibitor SB203580 on the p38-MAPK phosphorylation induced by extracellular alkalosis (pH 8.5). (A) Protein (50 µg) from hearts perfused without (Co) or with an alkaline (pH 8.5) Tris–Tyrode's solution for 2 min in the absence (–) or presence (+) of 1 µmol l^–1 SB203580 was assessed by immunoblot using phosphospecific anti-p38-MAPK (top) or anti-actin antibody (bottom). (B) Densitometric analysis of phospho-p38-MAPK bands by laser scanning. Results are means ± s.e.m. for three independent experiments. *P<0.05 vs control value.