Discharge properties of group III and IV muscle afferents

their responses to mechanical and metabolic stimuli.

Marc Kaufman, K. J. Rybicki

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

Static contraction of the hind limb muscles induced by electrical stimulation of the ventral roots has been firmly established to reflexly increase cardiovascular and ventilatory function. Moreover, Group III and IV afferents are known to compose the afferent arm of this reflex arc. The present experiments investigated the discharge properties of Group III and IV afferents whose activation is responsible for the pressor reflex response to static contraction. In general, we found that Group III afferents were more responsive to mechanical stimuli, such as distortion of their receptive fields and tendon stretch, than were Group IV afferents. In contrast, Group IV afferents were more responsive to ischemic contraction than were Group III afferents. In addition, equal percents of Group III and IV afferents were found to be stimulated by increasing interstitial potassium to levels that were similar to those found during muscular contraction. The afferents' response to potassium adapted within seconds, while the interstitial concentration of this ion remained elevated for several minutes. This rapidly adapting response casts doubt on the effectiveness of potassium as the metabolite that signals blood supply and demand in a working muscle are improperly matched.

Original languageEnglish (US)
JournalCirculation Research
Volume61
Issue number4 Pt 2
StatePublished - Jan 1 1987

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Potassium
Muscles
Reflex
Spinal Nerve Roots
Muscle Contraction
Tendons
Electric Stimulation
Arm
Extremities
Ions

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

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abstract = "Static contraction of the hind limb muscles induced by electrical stimulation of the ventral roots has been firmly established to reflexly increase cardiovascular and ventilatory function. Moreover, Group III and IV afferents are known to compose the afferent arm of this reflex arc. The present experiments investigated the discharge properties of Group III and IV afferents whose activation is responsible for the pressor reflex response to static contraction. In general, we found that Group III afferents were more responsive to mechanical stimuli, such as distortion of their receptive fields and tendon stretch, than were Group IV afferents. In contrast, Group IV afferents were more responsive to ischemic contraction than were Group III afferents. In addition, equal percents of Group III and IV afferents were found to be stimulated by increasing interstitial potassium to levels that were similar to those found during muscular contraction. The afferents' response to potassium adapted within seconds, while the interstitial concentration of this ion remained elevated for several minutes. This rapidly adapting response casts doubt on the effectiveness of potassium as the metabolite that signals blood supply and demand in a working muscle are improperly matched.",
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Discharge properties of group III and IV muscle afferents : their responses to mechanical and metabolic stimuli. / Kaufman, Marc; Rybicki, K. J.

In: Circulation Research, Vol. 61, No. 4 Pt 2, 01.01.1987.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Kaufman, Marc

AU - Rybicki, K. J.

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AB - Static contraction of the hind limb muscles induced by electrical stimulation of the ventral roots has been firmly established to reflexly increase cardiovascular and ventilatory function. Moreover, Group III and IV afferents are known to compose the afferent arm of this reflex arc. The present experiments investigated the discharge properties of Group III and IV afferents whose activation is responsible for the pressor reflex response to static contraction. In general, we found that Group III afferents were more responsive to mechanical stimuli, such as distortion of their receptive fields and tendon stretch, than were Group IV afferents. In contrast, Group IV afferents were more responsive to ischemic contraction than were Group III afferents. In addition, equal percents of Group III and IV afferents were found to be stimulated by increasing interstitial potassium to levels that were similar to those found during muscular contraction. The afferents' response to potassium adapted within seconds, while the interstitial concentration of this ion remained elevated for several minutes. This rapidly adapting response casts doubt on the effectiveness of potassium as the metabolite that signals blood supply and demand in a working muscle are improperly matched.

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