Impaired oxidative metabolism in exercising muscle from ALS patients

The pathogenic mechanism of selective loss of motor neurones. in amyotrophi c lateral sclerosis (ALS) is still poorly understood. Recently, research ev idence has suggested that mitochondrial dysfunction occurs in central nervo us system as well as in peripheral tissues from ALS patients. The aim of ou r study was to indirectly investigate in vivo oxidative metabolism of exerc ising muscle in a case history of patients affected by ALS. To this purpose 11 patients, 8 male and 3 female, mean age +/- SD: 52.4 +/- 11.1 years, pe rformed a bicycle incremental test for the assessment of lactate production . At rest, there was increased lactate concentration in patients: 2.77 +/- 0.79 vs. 1.48 +/- 0.49 mmol/l in normal controls (normal range: 0.67-2.47 m mol/l). Analysis of lactate curve during exercise showed a lactate producti on increase compared to controls. Furthermore, anaerobic lactate threshold was detected at 40-50% of the predicted normal power output, anticipated wi th respect to both normal subjects and non-ALS chronically denervated contr ols with comparable motor impairment (60-70%), suggesting that mitochondria l dysfunction can occur in exercising skeletal muscle from ALS patients. (C ) 2001 Elsevier Science B.V. All rights reserved.