Comparative analysis of metabolic and functional cardiac alterations in diet- and genetically induced mouse models of cardiac dysfunction.

Cardiac metabolism is highly adaptive, and distinct maladaptive remodeling processes may contribute to the development of cardiac dysfunction. Here, we compared the metabolic, structural, and functional adaptations of two murine models: C57BL/6J mice fed a high-fat, carbohydrate-free diet and New Zealand Obese mice maintained on a standard diet. Cardiac function was assessed by echocardiography, plasma metabolite profiles were analyzed, and cardiac proteomes were quantified by mass spectrometry. Proteomic data were computationally integrated into a kinetic model of cardiac central metabolism (CARDIOKIN1) to predict changes in substrate utilization and ATP production capacities under physiological nutrient conditions. Diet-induced metabolic stress led to cardiac dysfunction with preserved ejection fraction, characterized by mitochondrial dysfunction, impaired ATP production, inflammation, and reduced cardiac mass. Conversely, genetically induced obesity resulted in cardiac impairment with reduced ejection fraction associated with mild fibrosis, maintained ATP production, and substrate switching favoring fatty acid utilization. Proteomic and computational analyses revealed a coordinated downregulation of metabolic networks involved in oxidative phosphorylation, substrate transport, and energy production in both models, but with distinct profiles of metabolic inflexibility and mitochondrial efficiency. This study provides insights of how dietary versus genetic metabolic stress reprograms cardiac metabolism and structure, offering mechanistic insights into the diverse pathways leading to cardiac dysfunction. These insights may guide future strategies for metabolic intervention in heart failure subtypes.