ATP, phosphocreatine and lactate in exercising muscle in mitochondrial disease and McArdle's disease

We studied exercise-induced changes in the adenosine triphosphate (ATP), ph osphocreatine (PCr), and lactate levels in the skeletal muscle of mitochond rial patients and patients with McArdle's disease. Needle muscle biopsy spe cimens for biochemical measurement were obtained before and immediately aft er maximal short-term bicycle exercise test from 12 patients suffering from autosomal dominant and recessive forms of progressive external ophthalmopl egia and multiple deletions of mitochondrial DNA (adPEO. arPEO, respectivel y), five patients with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) 3243 A --> G point mutation, and four pat ients with McArdle's disease. Muscle ATP and PCr levels at rest or after ex ercise did not differ significantly from those of the controls in any patie nt group. In patients with mitochondrial disease, muscle lactate tended to be lower at rest and increase more during exercise than in controls, the mo st remarkable rise being measured in patients with adPEO with generalized m uscle symptoms and in patients with MELAS point mutation. In McArdle patien ts, the muscle lactate level decreased during exercise. No correlation was found between the muscle ATP and PCr levels and the respiratory chain enzym e activity. (C) 2001 Elsevier Science B.V. All rights reserved.