Abstract 19826: Cardiac DGAT1 Deficiency Decreases Triglyceride Turnover and Alters Substrate Utilization

Triglyceride (TG) metabolism in the heart has been suggested to regulate PPARα activity and fatty acid oxidation. Reduced TG content and turnover has also been shown in rodent models of heart failure. We found that patients with heart failure displayed decreased mRNA levels of diacylglycerol:acyltransferase 1 (DGAT1), the rate limiting enzyme in TG synthesis (0.56±0.06 fold of NF, p=0.0001) and a lower myocardial TG content (3.65±0.41 vs. 8.27±1.48 mg/g tissue in NF, n=8-11, p=0.019). Therefore we hypothesized reduced TG synthesis caused metabolic remodeling in heart failure. In mice with tamoxifen-inducible cardiac specific deletion of DGAT1 (iKO) TG turnover was reduced. 13C NMR spectroscopy in perfused hearts revealed a 30% reduction in incorporation of labeled fatty acids (FA) into TG in iKO (40 minute peak area 7.86±0.26 vs. 5.73±0.50) with no changes in total TG content. To test whether these changes affect myocardial energetics and contractile function, we simultaneously measured high energy phosph...