Low-frequency stimulation of group III and IV hind limb afferents evokes reflex pressor responses in decerebrate rats

Jonathan E. Harms, Steven W. Copp, Marc Kaufman

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Contraction of freely perfused hind limb muscles in decerebrate rats evokes the exercise pressor reflex, resulting in sympathetic activation and increased blood pressure. This reflex is propagated along mechanically sensitive group III and metabolically sensitive group IV afferent nerve fibers. Recent research by our laboratory has focused on the exaggeration of the exercise pressor reflex in decerebrate rats with simulated peripheral artery disease, which was induced by ligating the femoral artery for 72 h before the start of the experiment. Recently, we showed that ligating the femoral artery increased the responses of single fiber group III and IV triceps surae muscle afferents to static contraction. The objective of this study was to determine if electrical stimulation of group III and IV afferents at frequencies approximating those occurring during static contraction was capable of reflexively increasing arterial blood pressure. We directly stimulated muscle afferents in the absence of muscle contraction for both freely perfused and ligated rats. We established 0.25 Hz as the minimal stimulation frequency to observe a sustained blood pressure response. The blood pressure response increased in a graded fashion as both stimulus frequency and motor threshold were increased. Additionally, we observed similar blood pressure responses from both freely perfused and ligated rats, suggesting that spinal and medullary processing of group III and IV afferent input plays no role in augmenting the pressor response to contraction caused by femoral artery ligation.

Original languageEnglish (US)
Article numbere13001
JournalPhysiological reports
Volume4
Issue number20
DOIs
StatePublished - Oct 1 2016

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Reflex
Femoral Artery
Extremities
Blood Pressure
Muscles
Peripheral Arterial Disease
Muscle Contraction
Nerve Fibers
Electric Stimulation
Ligation
Arterial Pressure
Research

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

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abstract = "Contraction of freely perfused hind limb muscles in decerebrate rats evokes the exercise pressor reflex, resulting in sympathetic activation and increased blood pressure. This reflex is propagated along mechanically sensitive group III and metabolically sensitive group IV afferent nerve fibers. Recent research by our laboratory has focused on the exaggeration of the exercise pressor reflex in decerebrate rats with simulated peripheral artery disease, which was induced by ligating the femoral artery for 72 h before the start of the experiment. Recently, we showed that ligating the femoral artery increased the responses of single fiber group III and IV triceps surae muscle afferents to static contraction. The objective of this study was to determine if electrical stimulation of group III and IV afferents at frequencies approximating those occurring during static contraction was capable of reflexively increasing arterial blood pressure. We directly stimulated muscle afferents in the absence of muscle contraction for both freely perfused and ligated rats. We established 0.25 Hz as the minimal stimulation frequency to observe a sustained blood pressure response. The blood pressure response increased in a graded fashion as both stimulus frequency and motor threshold were increased. Additionally, we observed similar blood pressure responses from both freely perfused and ligated rats, suggesting that spinal and medullary processing of group III and IV afferent input plays no role in augmenting the pressor response to contraction caused by femoral artery ligation.",
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Low-frequency stimulation of group III and IV hind limb afferents evokes reflex pressor responses in decerebrate rats. / Harms, Jonathan E.; Copp, Steven W.; Kaufman, Marc.

In: Physiological reports, Vol. 4, No. 20, e13001, 01.10.2016.

Research output: Contribution to journalArticle

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