Mitochondrial dysfunction in exercise muscle from ALS patients.

Introduction. The pathogenetic mechanism of selective loss of motor neurons in ALS is still poorly understood. Recent research evidence suggests that oxidative stress and mitochondrial dysfunction may be important contributory factors to motor neuron injury. The aim of our study was to indirectly investigate oxidative metabolism in vivo, in contracting muscle, in a case history of patients affected by ALS. Materials and methods. To this purpose in 8 patients, 6 M and 2 F, age range: 39-73 years, a forearm submaximal test for lactate production evaluation was performed. Results. Basal lactate concentration was increased in 4 patients: 3.01±0.21 mmol/l (normal range: 0.67-2.47 mmol/l). Analysis of lactate curve during exercise showed an increased workload-corrected lactate production compared to controls. In one subject lactate did not recover 20 min after the end of test. There was no relationship between exercise lactate levels and residual force of examined muscles. Conclusion. Even if other factors, such as partial chronic denervation; have to be taken into account, these results suggest that mitochondrial dysfunction can occur in exercise skeletal muscle from ALS patients.