title: The relationship between anaerobic lactate threshold and plasma catecholamines during incremental exercise in hereditary spastic paraplegia.
abstract: Lower limb muscle chronic hyperactivity in hereditary spastic paraplegia (HSP) is the consequence of motor corticospinal tract involvement, which in turn has been hypothesized to be of mitochondrial origin. In order to assess skeletal muscle aerobic metabolism and sympathetic response during exercise in 10 HSP patients, we evaluated their blood lactate and catecholamine levels during an incremental workload bicycle exercise. Lactate, but not epinephrine or norepinephrine, levels were significantly higher in the HSP patients than in control subjects, in both resting conditions and during exercise. In the patients, the anaerobic lactate threshold was reached prematurely (at 50% of the predicted normal maximal power output) when compared to normal controls. This finding was not related to any specific muscle morphology or histochemical activity. Although other factors, including chronic spasticity and muscle deconditioning, have to be considered in the interpretation of our data, our results suggest the possible involvement of a mitochondrial mechanism, independently of sympathetic system overactivation, in exercising skeletal muscle of HSP patients.
authors.affiliation: Department of Neurosciences, Neurological Clinic, University of Pisa, Italy. gsicilia@neuro.med.unipi.it
authors.forename: Gabriele
authors.initials: G
authors.lastname: Siciliano
authors.forename: Livia
authors.initials: L
authors.lastname: Pasquali
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Manca
authors.forename: Alberto
authors.initials: A
authors.lastname: Del Corona
authors.forename: Alessandra
authors.initials: A
authors.lastname: Tessa
authors.forename: Clarice
authors.initials: C
authors.lastname: Patrono
authors.forename: Concetta
authors.initials: C
authors.lastname: Prontera
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Zucchelli
authors.forename: Filippo M
authors.initials: FM
authors.lastname: Santorelli
mesh_terms: D000328:Adult; D000368:Aged; D015308:Anaerobic Threshold / Q000502:physiology; D001706:Biopsy; D004837:Epinephrine / Q000097:blood*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007773:Lactates / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009638:Norepinephrine / Q000097:blood*; D005082:Physical Exertion / Q000502:physiology*; D015419:Spastic Paraplegia, Hereditary / Q000097:blood / Q000503:physiopathology*
chemical_list: D007773:Lactates; D009638:Norepinephrine; D004837:Epinephrine