title: Skeletal muscle changes in patients with obstructive sleep apnoea syndrome.
abstract: Previous studies have shown that chronic hypoxia leads to changes in skeletal muscle structure (fibre size and type) and activities of several bioenergetic enzymes. Whether this occurs also in conditions characterised by intermittent hypoxia, such as the obstructive sleep apnoea syndrome (OSAS), is unknown. To explore this possibility, we obtained a needle biopsy of the quadriceps femoris in 12 consecutive stable outpatients with severe OSAS (52 +/- 9 year, apnoea-hypopnoea index 70 +/- 14 h(-1)) (x +/- SD) and in six healthy volunteers (49 +/- 8 year), where we quantified fibre type, size and protein content, as well as phosphofructo-kinase (PFK) and cytochrome oxidase (CytOx) activities. We found that fibre-type distribution was similar in patients and controls. In contrast, the diameter of type II fibres (74 +/- 10 microm vs. 56 +/- 11 microm, P < 0.05) and protein content (100 +/- 14 vs. 88 +/- 8 microg/mg) was higher in patients with OSAS. Likewise, we observed upregulation of CytOx (0.93 +/- 0.38 vs. 0.40 +/- 0.22 microkat/mg protein, P < 0.01) and PFK activities (5.35 +/- 4.8 vs. 1.3 +/- 1.3 microkat/ mg protein, P < 0.05) in patients with OSAS. These results show that, paralleling which occurs in conditions characterised by continuous hypoxia, patients with OSAS (and intermittent hypoxia) also show structural and bioenergetic changes in their skeletal muscle.
authors.affiliation: Servei de Pneumologia and Unidad de Investigación, Hospital Universitari Son Dureta, C/Andrea Doria 55, Palma de Mallorca 07014, Spain. jsauleda@hsd.es
authors.forename: Jaume
authors.initials: J
authors.lastname: Sauleda
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: García-Palmer
authors.forename: Salvador
authors.initials: S
authors.lastname: Tarraga
authors.forename: Andreu
authors.initials: A
authors.lastname: Maimó
authors.forename: Andreu
authors.initials: A
authors.lastname: Palou
authors.forename: Alvar G N
authors.initials: AG
authors.lastname: Agustí
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003576:Electron Transport Complex IV / Q000032:analysis; D006801:Humans; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000473:pathology; D009124:Muscle Proteins / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000473:pathology*; D025221:Phosphofructokinases / Q000032:analysis; D012891:Sleep Apnea Syndromes / Q000473:pathology*; D018709:Statistics, Nonparametric
chemical_list: D009124:Muscle Proteins; D003576:Electron Transport Complex IV; D025221:Phosphofructokinases