Abstract
We evaluated altered cardiac metabolism in Zucker Spontaneously Hypertensive Fatty (ZSF1) rats fed an isocaloric high-fat diet versus normal chow using hyperpolarized (HP) [1-(13)C]pyruvate MR spectroscopic imaging (MRSI). This technique exploits remarkable signal enhancement to track the metabolic fate of injected HP [1-(13)C]pyruvate in vivo, allowing a simultaneous assessment of multiple metabolic pathways. The conversion of [1-(13)C]pyruvate to [1-(13)C]lactate (Lac) reflects anaerobic glycolysis activity, while the detection of (13)C-bicarbonate (Bic) indicates glucose oxidation. Our findings show that ZSF1 rats fed a high-fat diet exhibit a greater reliance on anaerobic glycolysis relative to glucose oxidation, and this metabolic shift can be detected in vivo in real time. This study demonstrates the feasibility of HP [1-(13)C]pyruvate MRSI for assessing diet-dependent metabolic shifts in the myocardium of ZSF1 obese rats, a widely used preclinical model for heart failure with preserved ejection fraction (HFpEF).