Hepatic Acetate is an Essential Fuel for the Heart during Energy-Deprived States

Energy supply is fundamental to cardiac performance, yet the mechanisms by which the heart adapts to nutrient scarcity remain incompletely understood. Here, we identify acetate as a pivotal metabolic substrate that sustains cardiac contractile function during fasting-induced energy deficiency. Fasted mice reveal significant elevation of circulating acetate derived from hepatic fatty acid catabolism. Physiological concentrations of acetate alone can maintain ex vivo beating and electrical stability in Langendorff-perfused hearts. Primary mouse cardiomyocytes preferentially utilize acetate under energy-restricted conditions, which is abolished by knockdown of mitochondrial Acss1, the enzyme responsible for converting acetate to acetyl-CoA. Isotopic tracing with 13C-acetate demonstrated selective cardiac uptake during fasting. In vivo, acetate supplementation preserved heart rate and systolic function in fasted wild-type mice but not in Acss1-deficient hearts. These findings reveal an Acss1-dependent metabolic pathway enabling the heart to harness hepatic acetate as an endogenous fuel, representing a nutrient stress-responsive adaptation based on inter-organ crosstalk and implying therapeutic potential of acetate to energy-deficient heart diseases.