RT Journal Article SR Electronic T1 Effects of sustained hypoxia on sternohyoid and diaphragm muscle during development JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1149 OP 1158 DO 10.1183/09031936.00139512 VO 43 IS 4 A1 Jayne C. Carberry A1 Clodagh McMorrow A1 Aidan Bradford A1 James F.X. Jones A1 Ken D. O’Halloran YR 2014 UL http://erj.ersjournals.com/content/43/4/1149.abstract AB Sustained hypoxia is a dominant feature of respiratory disease. Despite the clinical significance, the effects of sustained hypoxia on the form and function of respiratory muscle during development are relatively underexplored. Wistar rats were exposed to 1 week of sustained hypoxia (ambient pressure 450 mmHg) or normoxia at various time points during development. Sternohyoid and diaphragm muscle contractile and endurance properties were assessed in vitro. Muscle succinate dehydrogenase and myosin heavy chain composition were determined. The role of reactive oxygen species in hypoxia-induced muscle remodelling was assessed. Sustained hypoxia increased sternohyoid muscle force and fatigue in early but not late development, effects that persisted after return to normoxia. Hypoxia-induced sternohyoid muscle fatigue was not attributable to fibre type transitions or to a decrease in oxidative capacity. Chronic supplementation with the superoxide scavenger tempol did not prevent hypoxia-induced sternohyoid muscle fatigue, suggesting that mechanisms unrelated to oxidative stress underpin hypoxia-induced maladaptation in sternohyoid muscle. Sustained hypoxia had no effect on diaphragm muscle fatigue. We conclude that there are critical windows during development for hypoxia-induced airway dilator muscle maladaptation. Sustained hypoxia-induced impairment of upper airway muscle endurance may persist into later life. Upper airway muscle dysfunction could have deleterious consequences for the control of pharyngeal airway calibre in vivo. There are critical windows during development for hypoxia-induced airway dilator muscle maladaptation http://ow.ly/t7iVj