title: Structural and functional properties of an upper airway dilator muscle in aged obese male rats.
abstract: BACKGROUND
  Age, obesity and male sex are risk factors for the development of obstructive sleep apnoea syndrome.
  
  
  OBJECTIVE
  We examined structural and functional properties of the sternohyoid muscle in young lean and aged obese male rats. We hypothesized that the aged muscle would be vulnerable to oxidative stress (hypoxia).
  
  
  METHODS
  Isometric contractile and endurance properties of the sternohyoid muscle were assessed in vitro with or without the superoxide scavenger Tempol (10 mM). Muscle fibre size and density were determined by myosin heavy chain immunofluorescence. Succinate dehydrogenase (SDH) and glycerol-3- phosphate dehydrogenase (GPDH) enzyme activities were determined.
  
  
  RESULTS
  Fibre hypertrophy, increased fast twitch (type 2X) fibre density, decreased SDH activity and increased GPDH activity, together with increased force and fatigue, were observed in aged obese muscles compared to young lean muscles. Tempol treatment increased strength and sensitivity to stimulation. Hypoxic depression of force was ameliorated by antioxidant treatment with equivalent effects in young lean and aged obese muscle.
  
  
  CONCLUSIONS
  We conclude that the rat sternohyoid exhibits indefinite growth and is protected from oxidative stress as the animal ages.
authors: UCD School of Medicine and Medical Science, Health Sciences Centre, University College Dublin, Dublin, Ireland.
authors: J Richard
authors: JR
authors: Skelly
authors: Ruth A
authors: RA
authors: O'Connell
authors: James F X
authors: JF
authors: Jones
authors: Ken D
authors: KD
authors: O'Halloran
mesh_terms: D000375:Aging; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015687:Cell Hypoxia; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004558:Electric Stimulation; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009765:Obesity / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D012132:Respiratory Muscles / Q000187:drug effects / Q000503:physiopathology*; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D013113:Spin Labels
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D013113:Spin Labels; C001803:tempol