Figure 2. Steady-state energetics phosphate metabolites as functions of myocardial oxygen consumption.

A, model-predicted steady-state CrP/ATP level plotted as a function of oxygen consumption rate, , and compared to experimental data from canine heart in vivo. B, model-predicted steady-state ΔP_i/CrP plotted as a function of . C, model-predicted steady-state free energy of ATP hydrolysis, −ΔG_ATPase, is plotted as a function of . D, model-predicted steady-state cytoplasmic inorganic phosphate concentration, [P_i]_c and ADP, [ADP]_c, plotted as a functions of . E, model-predicted steady-state cytoplasmic ATP, [ATP]_c, plotted as a function of . F, model-predicted steady-state cytoplasmic CrP [CrP]_c, plotted as a function of . For all simulations, is varied by varying the rate of ATP hydrolysis, J_ATPase, in the cytoplasm. Experimental data are obtained from the following sources: ○, Zhang et al. (2005) (dobutamine + dopamine); ▵, Zhang et al. (2003), ◊, Gong et al. (2003) (dobutamine + dopamine); ▵, Ochiai et al. (2001) (dobutamine + dopamine); ▿, Gong et al. (1999), □, Bache et al. (1999) (dobutamine, dobutamine +dopamine). Here protocols used to elevate work load from baseline are indicated in parentheses. The values of J_ATPase corresponding to baseline and maximal , 0.36 and 1.2 mmol s⁻¹ (l cell)⁻¹, respectively, are indicated in A. Error bars indicate standard error.