Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle

Marc P Kaufman, G. A. Iwamoto, J. C. Longhurst, J. H. Mitchell

Research output: Contribution to journalArticle

153 Citations (Scopus)

Abstract

Capsaicin, injected into the arterial supply of the skinned hindlimb of dogs, evokes reflex increases in cardiovascular function. Moreover, the cardiovascular reflexes evoked by capsaicin are very similar to those evoked by static exercise. The afferent fibers initiating these reflex increases have not been identified electrophysiologically, although their endings are believed to be located in skeletal muscle. We have, therefore, attempted to determine which afferent fibers are stimulated by capsaicin. In anesthetized dogs, we recorded impulses from afferent fibers with endings in either the gastrocnemius or gracilis muscles and injected capsaicin (10-30 μg/kg) into the abdominal aorta. Capsaicin stimulated 24 of 34 group IV (C fiber) endings, but only 5 of 19 group III (Aδ fiber) endings. By contrast, bradykinin (0.5-1.5 μg/kg) stimulated 17 of 33 group IV endings and 9 of 19 group III endings. Impulse activity for the 24 group IV afferents stimulated by capsaicin increased from 0.7 ± 0.1 to a peak of 9.3 ± 1.4 imp/sec. Firing started 6 ± 1 seconds after injection and remained above control levels for 24 ± 5 seconds. Capsaicin had no significant effect on the firing rate of 30 group I and II muscle afferents. Our results suggest that group IV muscle afferents are primarily responsible for causing the reflex increases in cardiovascular function evoked by injecting capsaicin into the arterial supply of the skinned hindlimb of dogs. Moreover, capsaicin is likely to be a useful pharmacological tool with which to determine the reflex autonomic effects caused by stimulation of group IV muscle afferents.

Original languageEnglish (US)
Pages (from-to)133-139
Number of pages7
JournalCirculation Research
Volume50
Issue number1
StatePublished - 1982
Externally publishedYes

Fingerprint

Capsaicin
Bradykinin
Skeletal Muscle
Reflex
Dogs
Hindlimb
Muscles
Autonomic Agents
Abdominal Aorta
Pharmacology
Injections

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Kaufman, M. P., Iwamoto, G. A., Longhurst, J. C., & Mitchell, J. H. (1982). Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle. Circulation Research, 50(1), 133-139.

Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle. / Kaufman, Marc P; Iwamoto, G. A.; Longhurst, J. C.; Mitchell, J. H.

In: Circulation Research, Vol. 50, No. 1, 1982, p. 133-139.

Research output: Contribution to journalArticle

Kaufman, MP, Iwamoto, GA, Longhurst, JC & Mitchell, JH 1982, 'Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle', Circulation Research, vol. 50, no. 1, pp. 133-139.
Kaufman, Marc P ; Iwamoto, G. A. ; Longhurst, J. C. ; Mitchell, J. H. / Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle. In: Circulation Research. 1982 ; Vol. 50, No. 1. pp. 133-139.
@article{a47c697ffbe944b7832513368c2b7d6d,
title = "Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle",
abstract = "Capsaicin, injected into the arterial supply of the skinned hindlimb of dogs, evokes reflex increases in cardiovascular function. Moreover, the cardiovascular reflexes evoked by capsaicin are very similar to those evoked by static exercise. The afferent fibers initiating these reflex increases have not been identified electrophysiologically, although their endings are believed to be located in skeletal muscle. We have, therefore, attempted to determine which afferent fibers are stimulated by capsaicin. In anesthetized dogs, we recorded impulses from afferent fibers with endings in either the gastrocnemius or gracilis muscles and injected capsaicin (10-30 μg/kg) into the abdominal aorta. Capsaicin stimulated 24 of 34 group IV (C fiber) endings, but only 5 of 19 group III (Aδ fiber) endings. By contrast, bradykinin (0.5-1.5 μg/kg) stimulated 17 of 33 group IV endings and 9 of 19 group III endings. Impulse activity for the 24 group IV afferents stimulated by capsaicin increased from 0.7 ± 0.1 to a peak of 9.3 ± 1.4 imp/sec. Firing started 6 ± 1 seconds after injection and remained above control levels for 24 ± 5 seconds. Capsaicin had no significant effect on the firing rate of 30 group I and II muscle afferents. Our results suggest that group IV muscle afferents are primarily responsible for causing the reflex increases in cardiovascular function evoked by injecting capsaicin into the arterial supply of the skinned hindlimb of dogs. Moreover, capsaicin is likely to be a useful pharmacological tool with which to determine the reflex autonomic effects caused by stimulation of group IV muscle afferents.",
author = "Kaufman, {Marc P} and Iwamoto, {G. A.} and Longhurst, {J. C.} and Mitchell, {J. H.}",
year = "1982",
language = "English (US)",
volume = "50",
pages = "133--139",
journal = "Circulation Research",
issn = "0009-7330",
publisher = "Lippincott Williams and Wilkins",
number = "1",

}

TY - JOUR

T1 - Effects of capsaicin and bradykinin on afferent fibers with endings in skeletal muscle

AU - Kaufman, Marc P

AU - Iwamoto, G. A.

AU - Longhurst, J. C.

AU - Mitchell, J. H.

PY - 1982

Y1 - 1982

N2 - Capsaicin, injected into the arterial supply of the skinned hindlimb of dogs, evokes reflex increases in cardiovascular function. Moreover, the cardiovascular reflexes evoked by capsaicin are very similar to those evoked by static exercise. The afferent fibers initiating these reflex increases have not been identified electrophysiologically, although their endings are believed to be located in skeletal muscle. We have, therefore, attempted to determine which afferent fibers are stimulated by capsaicin. In anesthetized dogs, we recorded impulses from afferent fibers with endings in either the gastrocnemius or gracilis muscles and injected capsaicin (10-30 μg/kg) into the abdominal aorta. Capsaicin stimulated 24 of 34 group IV (C fiber) endings, but only 5 of 19 group III (Aδ fiber) endings. By contrast, bradykinin (0.5-1.5 μg/kg) stimulated 17 of 33 group IV endings and 9 of 19 group III endings. Impulse activity for the 24 group IV afferents stimulated by capsaicin increased from 0.7 ± 0.1 to a peak of 9.3 ± 1.4 imp/sec. Firing started 6 ± 1 seconds after injection and remained above control levels for 24 ± 5 seconds. Capsaicin had no significant effect on the firing rate of 30 group I and II muscle afferents. Our results suggest that group IV muscle afferents are primarily responsible for causing the reflex increases in cardiovascular function evoked by injecting capsaicin into the arterial supply of the skinned hindlimb of dogs. Moreover, capsaicin is likely to be a useful pharmacological tool with which to determine the reflex autonomic effects caused by stimulation of group IV muscle afferents.

AB - Capsaicin, injected into the arterial supply of the skinned hindlimb of dogs, evokes reflex increases in cardiovascular function. Moreover, the cardiovascular reflexes evoked by capsaicin are very similar to those evoked by static exercise. The afferent fibers initiating these reflex increases have not been identified electrophysiologically, although their endings are believed to be located in skeletal muscle. We have, therefore, attempted to determine which afferent fibers are stimulated by capsaicin. In anesthetized dogs, we recorded impulses from afferent fibers with endings in either the gastrocnemius or gracilis muscles and injected capsaicin (10-30 μg/kg) into the abdominal aorta. Capsaicin stimulated 24 of 34 group IV (C fiber) endings, but only 5 of 19 group III (Aδ fiber) endings. By contrast, bradykinin (0.5-1.5 μg/kg) stimulated 17 of 33 group IV endings and 9 of 19 group III endings. Impulse activity for the 24 group IV afferents stimulated by capsaicin increased from 0.7 ± 0.1 to a peak of 9.3 ± 1.4 imp/sec. Firing started 6 ± 1 seconds after injection and remained above control levels for 24 ± 5 seconds. Capsaicin had no significant effect on the firing rate of 30 group I and II muscle afferents. Our results suggest that group IV muscle afferents are primarily responsible for causing the reflex increases in cardiovascular function evoked by injecting capsaicin into the arterial supply of the skinned hindlimb of dogs. Moreover, capsaicin is likely to be a useful pharmacological tool with which to determine the reflex autonomic effects caused by stimulation of group IV muscle afferents.

UR - http://www.scopus.com/inward/record.url?scp=0020040997&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0020040997&partnerID=8YFLogxK

M3 - Article

C2 - 7053873

AN - SCOPUS:0020040997

VL - 50

SP - 133

EP - 139

JO - Circulation Research

JF - Circulation Research

SN - 0009-7330

IS - 1

ER -