Lactate metabolism during exercise in patients with mitochondrial myopathy

• Published in: Neuromuscular disorders : NMD Vol. 23; no. 8; pp. 629 - 636
• Main Authors: Jeppesen, Tina D., Orngreen, Mette C., Van Hall, Gerrit, Vissing, John
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.08.2013
• Subjects: Adult; Analysis of Variance; Blood Pressure - physiology; Burns; DNA, Mitochondrial - genetics; Epinephrine - metabolism; Exercise - physiology; Female; Gas Chromatography-Mass Spectrometry; Humans; Insulin - metabolism; Lactate acidosis; Lactate kinetics; Lactic Acid - metabolism; Male; Middle Aged; Mitochondrial Myopathies - genetics; Mitochondrial Myopathies - metabolism; Mitochondrial Myopathies - physiopathology; Mitochondrial myopathy; Mutation - genetics; Neurology; Norepinephrine - metabolism; Oxygen Consumption; Premature fatigue; Time Factors; Premature fatigue; Mitochondrial myopathy; Lactate acidosis; Lactate kinetics
• ISSN: 0960-8966; 1873-2364; 1873-2364
• DOI: 10.1016/j.nmd.2013.05.007

Patients with mitochondrial DNA mutations often have elevated plasma lactate at rest and during exercise, but it is unknown whether the high lactate levels are caused by a high production, an impaired oxidation or a combination. We studied lactate kinetics in 10 patients with mtDNA mutations and 10 matched healthy control subjects at rest and during cycle exercise with a combination of femoral arterio-venous differences of lactate, and lactate tracer dilution methodology. During exercise, lactate concentration and production rates were several-fold higher in patients, but despite mitochondrial dysfunction, lactate was oxidized in muscle to the same extent as in healthy control subjects. This surprisingly high ability to burn lactate in working muscle with defective mitochondria, probably relates to the variability of oxidative capacity among muscle fibers. The data suggests that lactate is not solely an indicator of impaired oxidative capacity, but an important fuel for oxidative metabolism, even in muscle with severely impaired mitochondrial function.