Hydroxylation of salicylate by the in vitro diaphragm

Evidence for hydroxyl radical production during fatigue

P. T. Diaz, Z. W. She, W. B. Davis, T. L. Clanton

Research output: Contribution to journalArticle

77 Citations (Scopus)

Abstract

There is increasing evidence that oxygen-derived free radicals produced during strenuous work by the diaphragm may contribute to diaphragm fatigue and/or injury. However, the precise identity of these oxygen radicals remains unknown, inasmuch as oxygen free radicals are extremely short lived and their detection in biologic systems is quite difficult. There is recent evidence that the salicylate-trapping method may be a useful means of monitoring tissue production of hydroxyl radical (·OH). This method is predicated on the fact that salicylate's phenolic ring can be attacked by ·OH at the 3 or 5 position to yield 2,3- or 2,5-dihydroxybenzoic acid (DHB). These metabolites are stable and can be identified by high-performance liquid chromatography (HPLC) coupled with electrochemical or ultraviolet detection. To test the hypothesis that hydroxylated salicylates are produced during diaphragm fatigue, we exposed in vitro rat diaphragm strips to a physiological saline solution containing 2.0 mM sodium salicylate for ~15 min. The solution was then removed, and the strips were fatigued (20 Hz, 200- ms train duration, 1 train/s) via phrenic nerve stimulation for 30 s-10 min. The diaphragm strips were subsequently homogenized, and the homogenate was analyzed by HPLC coupled with ultraviolet detection. Levels of 2,3-DHB were significantly higher in fatigued than in control nonfatigued strips. There was also a significant correlation between the amount of 2,3-DHB in the fatigued muscle and the accumulated tension-time product developed during fatigue, 2,5-DHB was not consistently identified in control or experimental strips. We conclude that hydroxylation of salicylates occurs during low- frequency fatigue in the in vitro rat diaphragm; this provides strong evidence for ·OH production in this setting. The analysis of hydroxylated salicylates by HPLC has potential utility in delineating the role of oxidant stress in the generation of diaphragm fatigue and/or injury.

Original languageEnglish (US)
Pages (from-to)540-545
Number of pages6
JournalJournal of Applied Physiology
Volume75
Issue number2
StatePublished - Jan 1 1993

Fingerprint

Salicylates
Hydroxylation
Diaphragm
Hydroxyl Radical
Fatigue
High Pressure Liquid Chromatography
Free Radicals
Reactive Oxygen Species
Sodium Salicylate
Muscle Tonus
Phrenic Nerve
Wounds and Injuries
In Vitro Techniques
Oxidants
Sodium Chloride
Oxygen
2,3-dihydroxybenzoic acid

Keywords

  • free radicals
  • high- performance liquid chromatography
  • hydroxybenzoic acids
  • rats
  • respiratory muscles

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Hydroxylation of salicylate by the in vitro diaphragm : Evidence for hydroxyl radical production during fatigue. / Diaz, P. T.; She, Z. W.; Davis, W. B.; Clanton, T. L.

In: Journal of Applied Physiology, Vol. 75, No. 2, 01.01.1993, p. 540-545.

Research output: Contribution to journalArticle

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