Energy substrate metabolism in cardiac hypertrophy.

Cardiac hypertrophy is a response to long-term pathologic (eg, hypertension) or physiologic (eg, exercise) hemodynamic overload accompanied by changes in energy substrate utilization. The pattern of substrate utilization (or metabolic phenotype) differs dramatically between pathologic and physiologic cardiac hypertrophy with directionally opposite changes in oxidation of fatty acids and glucose and glycolysis. These findings indicate that the metabolic response to long-term alterations in hemodynamic workload is not stereotypical, but is influenced by the nature of the stimulus leading to cardiac hypertrophy. Although the changes in substrate utilization are adaptive, in the case of pathologic stimuli, the changes in metabolism interfere with functional resiliency of the heart to metabolic stress, as occurs during ischemia-reperfusion. The distinct metabolic phenotypes of hearts hypertrophied in response to pathologic or physiologic stimuli are due not only to alteration in expression of metabolic enzymes and proteins, but also to post-translational modulation of metabolic enzymes and proteins.