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Tempol, a SOD‐mimetic, improves rat pharyngeal dilator muscle performance during hyperoxia and hypoxia
Author(s) -
Skelly James Richard,
Mitchell Gordon S,
Bradford Aidan,
O'Halloran Ken D.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.739.3
Subject(s) - dilator , hyperoxia , isometric exercise , hypoxia (environmental) , medicine , muscle fatigue , inotrope , contractility , sildenafil , tiron , endocrinology , anesthesia , chemistry , electromyography , lung , biochemistry , physical medicine and rehabilitation , organic chemistry , oxygen , enzyme , superoxide
Agents that improve respiratory muscle performance may be useful as an adjunct treatment for obstructive sleep apnoea. The aim of this study was to examine the effects of antioxidants on rat pharyngeal dilator muscle contractile and endurance properties. Isometric contractile and endurance properties of isolated strips of sternohyoid muscle were examined in tissue baths under hyperoxic (95%O2/5%CO2) or hypoxic (95%N2/5%CO2) conditions in the absence (control) or presence of the antioxidants: N‐acetyl cysteine (NAC, 10mM), Tiron (10mM) or Tempol (10mM). Specific force (Sf) was measured at stimulus frequencies from 10–100Hz and throughout a standard fatigue trial (40Hz for 300msec every 2 seconds for 2 minutes). Under hyperoxic conditions, Tempol had an inotropic effect over initial 90s of fatigue (Sf at 90s was 3.7 ± 0.5 vs. 7.7 ± 0.4 N/cm2, control (n=9) vs. Tempol‐incubated (n=9) muscles, P<0.05 ANOVA). In hypoxia, Tempol significantly increased force over the initial 50s of fatigue (Sf at 50s was 1.3 ± 0.2 vs. 2.9 ± 0.5 N/cm2, control (n=9) vs. Tempol‐incubated (n=9) muscles, P<0.05 ANOVA). NAC had no significant effect and Tiron had weak inotropic effects on sternohyoid muscle function. This study illustrates that the SOD mimetic, Tempol, has inotropic effects on sternohyoid muscle during fatiguing and non‐fatiguing contractions. We conclude that antioxidants may be beneficial in the treatment of OSA.