Remodeling of substrate consumption in the murine sTAC model of heart failure

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Item Type:	Article
Title:	Remodeling of substrate consumption in the murine sTAC model of heart failure
Creators Name:	Turer, A., Altamirano, F., Schiattarella, G., May, H., Gillette, T.G., Malloy, C.R. and Merritt, M.E.
Abstract:	BACKGROUND: Energy metabolism and substrate selection are key aspects of correct myocardial mechanical function. Myocardial preference for oxidizable substrates changes in both hypertrophy and in overt failure. Previous work has shown that glucose oxidation is upregulated in overpressure hypertrophy, but its fate in overt failure is less clear. Anaplerotic flux of pyruvate into the tricarboxylic acid cycle (TCA) has been posited as a secondary fate of glycolysis, aside from pyruvate oxidation or lactate production. METHODS AND RESULTS: A model of heart failure that emulates both valvular and hypertensive heart disease, the severe transaortic constriction (sTAC) mouse, was assayed for changes in substrate preference using metabolomic and carbon-13 flux measurements. Quantitative measures of O(2) consumption in the Langendorff perfused mouse heart were paired with (13)C isotopomer analysis to assess TCA cycle turnover. Since the heart accommodates oxidation of all physiological energy sources, the utilization of carbohydrates, fatty acids, and ketones were measured simultaneously using a triple-tracer NMR method. The fractional contribution of glucose to acetyl-CoA production was upregulated in heart failure, while other sources were not significantly different. A model that includes both pyruvate carboxylation and anaplerosis through succinyl-CoA produced superior fits to the data compared to a model using only pyruvate carboxylation. In the sTAC heart, anaplerosis through succinyl-CoA is elevated, while pyruvate carboxylation was not. Metabolomic data showed depleted TCA cycle intermediate pool sizes versus the control, in agreement with previous results. CONCLUSION: In the sTAC heart failure model, the glucose contribution to acetyl-CoA production was significantly higher, with compensatory changes in fatty acid and ketone oxidation not reaching a significant level. Anaplerosis through succinyl-CoA is also upregulated, and is likely used to preserve TCA cycle intermediate pool sizes. The triple tracer method used here is new, and can be used to assess sources of acetyl-CoA production in any oxidative tissue.
Keywords:	Substrate Selection, Glucose, Ketones, Fatty Acids, Anaplerosis, Animals, Mice
Source:	Journal of Molecular and Cellular Cardiology
ISSN:	0022-2828
Publisher:	Elsevier
Volume:	134
Page Range:	144-153
Date:	September 2019
Official Publication:	https://doi.org/10.1016/j.yjmcc.2019.07.007
PubMed:	View item in PubMed

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