Fig. 1.

Steady-state energetics phosphate metabolites as functions of myocardial oxygen consumption in normal and LVH hearts. Simulations are plotted as solid curves in A and B for the normal heart, C and D for the early-stage LVH heart, and E and F for the moderate LVH heart. Steady-state CrP/ATP level is plotted as a function of oxygen consumption rate, MVO₂, and compared with experimental data from the normal (A), early-stage LVH (C), and moderate LVH (E) canine heart in vivo. Steady-state ΔPi/CrP plotted as a function of MVO₂ and compared with experimental data from the normal (B), early-stage LVH (D), and moderate LVH (F) canine heart in vivo. For model predictions, MVO₂ is varied by varying the rate of ATP hydrolysis, J_ATPase, in the cytoplasm. The model for the normal control case (A and B) is described in Wu et al. (2). Experimental data shown in A and B are obtained from the following sources: open circles, Zhang et al. (21) (dobutamine + dopamine); open left-facing triangles, Zhang et al. (22); open diamonds, Gong et al. (16) (dobutamine + dopamine); open triangles, Ochiai et al. (23) (dobutamine + dopamine); open inverted triangles, Gong et al. (24); squares, Bache et al. (6) (dobutamine, dobutamine + dopamine). The experimental data for the early-stage and moderate LVH hearts are plotted as open circles and obtained from refs. 7 and 6, respectively. Here protocols used to elevate work load from baseline are indicated in parentheses. The values of J_ATPase corresponding to baseline and maximal MVO₂, 0.36 and 1.2 mmol s⁻¹ (l cell)⁻¹, respectively, are indicated in A. Error bars indicate standard error.