Abstract 873: Acetate Protects the Heart Against Ischemic Injury by Alternating TCA Cycle-related Metabolites and AMP-activated Protein Kinase

Introduction: Acetate is preferentially taken up in the heart, and converted into acetyl-CoA by acetyl-CoA synthetase2 (AceCS2), which is abundant in the mitochondria of cardiomyocytes, resulting in activation of AMPK through an elevation of AMP/ATP ratio. In this context, we investigated the effects of acetate on myocardial ischemic injury in isolated cardiomyocytes and in vivo mouse hearts.

Methods and Results: In isolated cardiomyocytes, 13 C-labelled metabolites were analyzed using capillary electrophoresis-electrospray ionization mass spectroscopy (CE-ESI-MS) in order to determine the fate of exogenously administered 13 C-acetate. The oxygen consumption rate (OCR) was evaluated using a flux analyzer. A variety of 13 C-labelled intermediates in the TCA cycle increased 10 minutes after administration of 13 C-acetate followed by a subsequent increase in OCR. The OCR elevation was sustained more than 2 hours after acetate injection. The acetate-induced OCR elevation was partially blocked by the glycolysis inhibitor 2-Deoxyglucose (2-DG), carnitine palmitoyl transferase1A (CPT-1A) inhibitor (etomoxir), and mitochondrial pyruvate carrier (MPC) inhibitor (UK5099). The acetate-induced OCR elevation was also blocked by AMP-activated protein kinase (AMPK) inhibitor (compound C). These findings indicated that acetate caused an elevation in mitochondrial function through activation of various metabolic pathways, which may be related to activation of the AMPK pathway. Next, left anterior descending artery-ligated hearts were processed with focused microwave and analyzed by CE-MS and matrix-assisted laser desorption/ionization imaging mass spectrometry in order to examine the region-specific metabolite changes at the early phase of ischemia. Nicotinamide adenine dinucleotide (NADH) elevation in the ischemic core region was suppressed by acetate administration. Furthermore, acetate inhibited cardiac remodeling in a protective manner several weeks after myocardial ischemia when viewed by cardiac ultrasound.

Conclusion: Acetate caused an increase in OCR via both a significant elevation in TCA cycle metabolites and activation of AMPK pathway, and may have a protective effect on myocardial ischemic injury.