Aims: Development of heart failure is known to be associated with changes in energy substrate metabolism. Information on the changes in energy substrate metabolism that occur in heart failure is limited and results vary depending on the methods employed. Our aim is to characterize the changes in energy substrate metabolism associated with pressure overload and ischaemia-reperfusion (I/R) injury.
Methods and results: We used transverse aortic constriction (TAC) in mice to induce pressure overload-induced heart failure. Metabolic rates were measured in isolated working hearts perfused at physiological afterload (80 mmHg) using (3)H- or (14)C-labelled substrates. As a result of pressure-overload injury, murine hearts exhibited: (i) hypertrophy, systolic, and diastolic dysfunctions; (ii) reduction in LV work, (iii) reduced rates of glucose and lactate oxidations, with no change in glycolysis or fatty acid oxidation and a small decrease in triacylglycerol oxidation, and (iv) increased phosphorylation of AMPK and a reduction in malonyl-CoA levels. Sham hearts produced more acetyl CoA from carbohydrates than from fats, whereas TAC hearts showed a reverse trend. I/R in sham group produced a metabolic switch analogous to the TAC-induced shift to fatty acid oxidation, whereas I/R in TAC hearts greatly exacerbated the existing imbalance, and was associated with a poorer recovery during reperfusion.
Conclusions: Pressure overload-induced heart failure and I/R shift the preference of substrate oxidation from glucose and lactate to fatty acid due to a selective reduction in carbohydrate oxidation. Normalizing the balance between metabolic substrate utilization may alleviate pressure-overload-induced heart failure and ischaemia.