FIGURE 2.

Events underlying cross-bridge metabolism. (A) The creatine-phosphokinase (Lohmann) reaction. Note the relative independence of ATP and PCr concentrations until the latter is nearly exhausted [based on Figure 4.2, Page 142 of Woledge et al. (1985)] (B) The Gibbs Free Energy of ATP hydrolysis as a function of the progressively increasing concentration of inorganic phosphate (Pi) in the absence of mitochondrial function, reflecting events shown in (A): G_ATP = ΔG^o + RTln⁡([ADP][Pi]/[ATP]), where the Standard Gibbs Free Energy of ATP hydrolysis, $G_{ATP}^o=-30kJ/mol$, R is the Universal Gas Constant (8.31 kJ/mol), T is absolute temperature (310 K), and [ATP] and [ADP] are assumed to be 5 mmol/L and 1 μmol/L, respectively, under steady-state conditions of twitch force production. (Note the inverse scale on the ordinate).