Preservation of myocardial fatty acid oxidation prevents diastolic dysfunction in mice subjected to angiotensin II infusion

- Deletion of ACC2 in adult mouse heart increases fatty acid oxidation.
- Maintaining cardiac fatty acid oxidation during Angiotensin II infusion prevents diastolic dysfunction.
- Sustained fatty acid oxidation protects mitochondria and reduces myocardial oxidative stress.
- Mitochondrial fatty acid oxidation is a viable therapy for pathological hypertrophy.

RationaleDiastolic dysfunction is a common feature in many heart failure patients with preserved ejection fraction and has been associated with altered myocardial metabolism in hypertensive and diabetic patients. Therefore, metabolic interventions to improve diastolic function are warranted. In mice with a germline cardiac-specific deletion of acetyl CoA carboxylase 2 (ACC2), systolic dysfunction induced by pressure-overload was prevented by maintaining cardiac fatty acid oxidation (FAO). However, it has not been evaluated whether this strategy would prevent the development of diastolic dysfunction in the adult heart.ObjectiveTo test the hypothesis that augmenting cardiac FAO is protective against angiotensin II (AngII)-induced diastolic dysfunction in an adult mouse heart.Methods and resultsWe generated a mouse model to induce cardiac-specific deletion of ACC2 in adult mice. Tamoxifen treatment (20 mg/kg/day for 5 days) was sufficient to delete ACC2 protein and increase cardiac FAO by 50% in ACC2 flox/flox-MerCreMer+ mice (iKO). After 4 weeks of AngII (1.1 mg/kg/day), delivered by osmotic mini-pumps, iKO mice showed normalized E/E′ and E′/A′ ratios compared to AngII treated controls (CON). The prevention of diastolic dysfunction in iKO-AngII was accompanied by maintained FAO and reduced glycolysis and anaplerosis. Furthermore, iKO-AngII hearts had a ~ 50% attenuation of cardiac hypertrophy and fibrosis compared to CON. In addition, maintenance of FAO in iKO hearts suppressed AngII-associated increases in oxidative stress and sustained mitochondrial respiratory complex activities.ConclusionThese data demonstrate that impaired FAO is a contributor to the development of diastolic dysfunction induced by AngII. Maintenance of FAO in this model leads to an attenuation of hypertrophy, reduces fibrosis, suppresses increases in oxidative stress, and maintains mitochondrial function. Therefore, targeting mitochondrial FAO is a promising therapeutic strategy for the treatment of diastolic dysfunction.