Key result
In mice fed a high fat, high sucrose diet, metabolic heart disease is characterized by decreased ATP production leading to energetic deficiency and elevated [ADP], with preserved CK flux.
Why the study?
Does a high fat, high sucrose diet induce myocardial energetic deficiency and pump dysfunction in mice?
Does a high fat, high sucrose diet induce myocardial energetic deficiency and pump dysfunction in mice?
Metabolic heart disease in mice is characterized by decreased ATP production and elevated ADP with preserved creatine kinase flux, distinguishing its metabolic phenotype from dilated cardiomyopathy.
May suggest ATP synthesis as therapeutic target in metabolic cardiomyopathy; leaves open translation to human disease.
Metabolic syndrome is a cluster of obesity-related metabolic abnormalities that lead to metabolic heart disease (MHD) with left ventricular pump dysfunction. Although MHD is thought to be associated with myocardial energetic deficiency, two key questions have not been answered. First, it is not known whether there is a sufficient energy deficit to contribute to pump dysfunction. Second, the basis for the energy deficit is not clear. To address these questions, mice were fed a high fat, high sucrose (HFHS) ‘Western' diet to recapitulate the MHD phenotype. In isolated beating hearts, we used 31 P NMR spectroscopy with magnetization transfer to determine a) the concentrations of high energy phosphates ([ATP], [ADP], [PCr]), b) the free energy of ATP hydrolysis (∆G ~ATP ), c) the rate of ATP production and d) flux through the creatine kinase (CK) reaction. At the lowest workload, the diastolic pressure-volume relationship was shifted upward in HFHS hearts, indicative of diastolic dysfunction, whereas systolic function was preserved. At this workload, the rate of ATP synthesis was decreased in HFHS hearts, and was associated with decreases in both [PCr] and ∆G ~ATP . Higher work demands unmasked the inability of HFHS hearts to increase systolic function and led to a further decrease in ∆G ~ATP to a level that is not sufficient to maintain normal function of sarcoplasmic Ca 2+ -ATPase (SERCA). While [ATP] was preserved at all work demands in HFHS hearts, the progressive increase in [ADP] led to a decrease in ∆G ~ATP with increased work demands. Surprisingly, CK flux, CK activity and total creatine were normal in HFHS hearts. These findings differ from dilated cardiomyopathy, in which the energetic deficiency is associated with decreases in CK flux, CK activity and total creatine. Thus, in HFHS-fed mice with MHD there is a distinct metabolic phenotype of the heart characterized by a decrease in ATP production that leads to a functionally-important energetic deficiency and an elevation of [ADP], with preservation of CK flux.
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Luptak et al. (2018) studied Metabolic heart disease. High fat, high sucrose (HFHS) 'Western' diet was evaluated on Myocardial energetic deficiency and pump dysfunction. In mice fed a high fat, high sucrose diet, metabolic heart disease is characterized by decreased ATP production leading to energetic deficiency and elevated [ADP], with preserved CK flux.
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