Myocardial energetics in cardiac hypertrophy.

1. This review is presented with the intent of illustrating the representative studies of functional and myocardial energetic consequences of hearts with postinfarction left ventricular (LV) remodelling or with concentric hypertrophy and diastolic LV dysfunction in porcine models. 2. Both eccentric and concentric cardiac hypertrophy are associated with the abnormal myocardial energetics that are most severe in hearts with congestive heart failure (CHF). Presently, these abnormalities cannot be satisfactorily explained to be the cause(s) of the dysfunction of failing hearts or cause the progress from compensated cardiac hypertrophy to CHF. 3. Mechanisms governing abnormal myocardial high-energy phosphate (HEP) metabolism in hearts with cardiac hypertrophy and CHF are unclear. Myocardial energy metabolism studies use both kinetic and thermodynamic models. The thermodynamic studies examine the myocardial steady state levels of high- and low-energy phosphate, which indicate myocardial energy state or phosphorylation potential that is defined by the ratio of [ATP]/([ADP][Pi]). The kinetics studies examine the reaction velocity that is regulated by: (i) quantity and activity of the key enzymes; (ii) the concentrations of all the substrates and products; and (iii) the Michaelis-Menten constants of each substrate of the reaction. 4. Significant alterations in myocardial concentrations of phosphocreatine (PCr), ATP and ADP, myocardial oxidative phosphorylation (OXPHOS) protein expression and substrate preference are found in hearts with postinfarction LV remodelling and CHF. However, to define a causal relationship is a different matter. 5. Future studies of animal models of LV hypertrophy or heart failure using gene manipulation may provide additional insights to answer the persisting question of whether limitations of ATP synthetic or transport capacities contribute to the pathogenesis of LV remodelling or failure.