Sensitization of group III muscle afferents to static contraction by arachidonic acid

D. M. Rotto, H. D. Schultz, J. C. Longhurst, Marc P Kaufman

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107 Scopus citations

Abstract

The afferent arm of the reflex arc responsible for the pressor response to static contraction is comprised of group III and IV fibers. The nature of the contraction-induced stimulus activating these fibers remains unclear. Evidence suggests that most group III afferents are sensitive to mechanical stimuli, whereas most group IV afferents are sensitive metabolic stimuli. Recently, in anesthetized cats, stimulation of group III mechanoreceptors has been shown to have a role in the reflex pressor response to static contraction. In skin, the sensitivity of thin fiber mechanoreceptors to distortion of their receptive fields has been shown to be increased by both cyclooxygenase and lipoxygenase products of arachidonic acid metabolism. Therefore, in barbiturate-anesthetized cats we recorded the responses of group III muscle afferents to static contraction before and after arachidonic acid (1-2 mg ia) and/or indomethacin (5 mg/kg iv). Arachidonic acid increased the responses of group III afferents (n = 11) to contraction by 265% (from 0.17 ± 0.07 to 0.62 ± 0.24 impulses/s; P < 0.025). Indomethacin decreased the responses of group III afferents (n = 9) to contraction by 61% (from 1.00 ± 0.37 to 0.39 ± 0.16 impulses/s; P < 0.025). Arachidonic acid given after indomethacin increased the responses of two of four group III afferents to contraction. We conclude that both cyclooxygenase and lipoxygenase products of arachidonic acid metabolism sensitize group III muscle afferents to static contraction.

Original languageEnglish (US)
Pages (from-to)861-867
Number of pages7
JournalJournal of Applied Physiology
Volume68
Issue number3
StatePublished - 1990

Keywords

  • dorsal root afferents
  • exercise
  • indomethacin
  • leukotrienes
  • prostaglandins and thromboxanes
  • reflex control of the autonomic nervous system

ASJC Scopus subject areas

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

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