Fig. 3. Time-dependent changes of PCr (circles) and La (squares) concentrations (A) and pHi (inverted triangles) and pHe (diamonds) values (B) are shown. All the data are from the additional set of experiments performed at 25°C where initial pHe value was 7.9 and the muscle pHi initial values were varied: high (filled symbols; preparation 1) and low (open symbols; preparation 2). The brackets in B indicate the corresponding pHi and pHe values (i.e. the proton gradient).