Antioxidant Treatment Does Not Prevent Chronic Hypoxia-Induced Respiratory Muscle Impairment in Developing Rats
Litters of rats were exposed to normobaric normoxia or hypobaric hypoxia (PB= 450 mmHg) for 7 days at 3 different time points during early development (postnatal day (P)1, P6 & P11). A separate litter exposed to hypoxia at P11 was treated with the antioxidant Tempol (100 mg/kg) given by oral administration daily starting at P8. At P19, sternohyoid and diaphragm muscles were removed and isolated muscle bundles were mounted isometrically in physiological salt solution at 30°C in vitro. Fatigue was assessed in response to repeated stimulation (40 Hz) every 2 s for 5 min. Fatigue index was measured. Chronic hypoxia decreased sternohyoid, but not diaphragm, muscle endurance. Tempol treatment did not prevent hypoxia-induced muscle plasticity, suggesting that reactive oxygen species are not implicated in hypoxia-induced muscle dysfunction.
KeywordsFatigue Platinum Superoxide NaH2PO4 Gluconate
Supported by the Health Research Board, Ireland and UCD.
- Skelly, J. R., Bradford, A. et al. (2009) Superoxide Scavengers Improve Rat Pharyngeal Dilator Muscle Performance. Am. J. Respir. Cell Mol. Biol. Google Scholar
- Supinski, G., Nethery, D. et al. (1997) Effect of free radical scavengers on diaphragmatic fatigue. Am. J. Respir. Crit. Care Med. 155(2), 622–629.Google Scholar