Increased superoxide production during fatigue in the perfused rat diaphragm

Ralph C. Kolbeck, Zhi Wu She, Leigh A. Callahan, Thomas M. Nosek

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


This study test the hypothesis that a temporal relationship exists between the production of superoxide anion (O2-) and the contractile activity of perfused rat diaphragm. O2- levels were determined minute to minute by measuring the reduction of cytochrome c in the perfusate as the diaphragms were subjected to various levels of contractile activity. After equilibrating at low contractile rates (one 500 ms 80 Hz train/min), diaphragms were fatigued by increasing their contractile activity for 5 min (one 500 ms 80 Hz train/s) and then allowed to recover for 30 min (one 500 ms 80 Hz train/min). During equilibration, diaphragms did not produce O2- above the background level measured in the presence of superoxide dismutase (SOD). Within the first minute of fatigue-inducing stimulation, however, the rate of O2- production increased to 0.70 ± 0.17 nmol/min and remained elevated until the recovery period when production returned towards baseline. SOD blocked this stimulation-related increase of O2- . Tension (± SOD) fell to 12% of the control value during the fatigue-inducing stimulation. During recovery the contractile response returned to 51% of control, indicating long-lasting effects on the contractile machinery. SOD did not limit fatigue or improve recovery, probably because it is a large protein that cannot cross cell membranes and protect the cells by scavenging O2- at its site of production.

Original languageEnglish
Pages (from-to)140-145
Number of pages6
JournalAmerican Journal of Respiratory and Critical Care Medicine
Issue number1
StatePublished - 1997

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine


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