Triacylglycerol infusion does not improve hyperlactemia in resting patients with mitochondrial myopathy due to complex I deficiency

Background: A high-fat diet has been recommended for correction of biochemical abnormalities and muscle energy state in patients with complex I (NADH dehydrogenase) deficiency (CID). Objective: This study evaluated the effects of intravenous infusion of isoenergetic amounts of triacylglycerol or glucose on substrate oxidation, glycolytic carbohydrate metabolism, and energy state in patients with CID. Design: Four CID patients and 15 matched control subjects were infused with triacylglycerol (1.85 mg(.)kg(-1.)min(-1)) or glucose (5 mg(.)kg(-1.)min(-1)) while at rest. Respiratory calorimetry was used to evaluate mitochondrial substrate oxidation. Metabolism of glycolytic carbohydrate was determined on the basis of the rates of appearance and concentrations of plasma lactate from dilution of [1-C-13]lactate measurements. In addition, high-energy phosphate metabolism was measured in forearm muscle by P-31 magnetic resonance spectroscopy. Results: Whole-body oxygen consumption rates were higher in the patients than in the control subjects (P