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. 1969 Dec;205(3):527–548. doi: 10.1113/jphysiol.1969.sp008981

A study of chemoreceptor and baroreceptor A and C-fibres in the cat carotid nerve

S J Fidone, A Sato
PMCID: PMC1348567  PMID: 5361289

Abstract

1. 149 A-fibres and 52 C-fibres from the cat carotid nerve were studied in vivo with single-unit recording techniques. These units subserved chemoreceptor and baroreceptor modalities. In addition, half of the C-fibres were determined to be efferent in origin. The estimated fibre diameter spectrum for chemoreceptor and baroreceptor A-fibres is described.

2. The discharge pattern of chemoreceptor A and C-fibres was characteristically irregular both at rest and during activation. However, about 5% of the chemoreceptor A-fibre population exhibited a very regular discharge pattern, even at low rates of firing.

3. In comparing A and C-fibres, it was found that chemoreceptor and baroreceptor A-fibres had lower thresholds, shorter response latencies, more rapid acceleration of discharge and higher discharge frequencies than their C-fibre counterparts.

4. During strong chemoreceptor or baroreceptor stimulation, interaction of the `spontaneous' whole nerve activity with the evoked A and C-fibre compound action potentials provided a method of estimating the relative proportions of chemoreceptors and baroreceptors in the A and C-fibre populations of the carotid nerve. The A-fibre population was found to be comprised of approximately 2/3 chemoreceptors, 1/3 baroreceptors. The reverse was true for the C-fibre population, i.e. 2/3 baroreceptors, 1/3 chemoreceptors.

5. A stepwise C-fibre response is described which may arise from the several C-fibres within a single Schwann cell.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. ARMETT C. J., RITCHIE J. M. The action of acetylcholine on conduction in mammalian non-myelinated fibres and its prevention by an anticholinesterase. J Physiol. 1960 Jun;152:141–158. doi: 10.1113/jphysiol.1960.sp006476. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Armett C. J., Ritchie J. M. The ionic requirements for the action of acetylcholine on mammalian non-myelinated fibres. J Physiol. 1963 Jan;165(1):141–159. doi: 10.1113/jphysiol.1963.sp007048. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. BISCOE T. J., TAYLOR A. THE DISCHARGE PATTERN RECORDED IN CHEMORECEPTOR AFFERENT FIBRES FROM THE CAT CAROTID BODY WITH NORMAL CIRCULATION AND DURING PERFUSION. J Physiol. 1963 Sep;168:332–344. doi: 10.1113/jphysiol.1963.sp007195. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Biscoe T. J., Sampson S. R. Rhythmical and non-rhythmical spontaneous activity recorded from the central cut end of the sinus nerve. J Physiol. 1968 May;196(2):327–338. doi: 10.1113/jphysiol.1968.sp008510. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. DE CASTRO F. Sur la structure de la synapse dans les chemocepteurs; leur mécanisme d'excitation et rôle dans la circulation sanguine locale. Acta Physiol Scand. 1951 Feb 21;22(1):14–43. doi: 10.1111/j.1748-1716.1951.tb00747.x. [DOI] [PubMed] [Google Scholar]
  6. DOUGLAS W. W., RITCHIE J. M. A technique for recording functional activity in specific groups of medullated and non-medullated fibres in whole nerve trunks. J Physiol. 1957 Aug 29;138(1):19–30. doi: 10.1113/jphysiol.1957.sp005835. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. DOUGLAS W. W., RITCHIE J. M. Cardiovascular reflexes produced by electrical excitation of non-medullated afferents in the vagus, carotid sinus and aortic nerves. J Physiol. 1956 Oct 29;134(1):167–178. doi: 10.1113/jphysiol.1956.sp005632. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. EYZAGUIRRE C., LEWIN J. Effect of different oxygen tensions on the carotid body in vitro. J Physiol. 1961 Dec;159:238–250. doi: 10.1113/jphysiol.1961.sp006805. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. EYZAGUIRRE C., LEWIN J. The effect of sympathetic stimulation on carotid nerve activity. J Physiol. 1961 Dec;159:251–267. doi: 10.1113/jphysiol.1961.sp006806. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. EYZAGUIRRE C., UCHIZONO K. Observations on the fibre content of nerves reaching the carotid body of the cat. J Physiol. 1961 Dec;159:268–281. doi: 10.1113/jphysiol.1961.sp006807. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Fidone S., Sato A., Eyzaguirre C. Acetylcholine activation of carotid body chemoreceptor A fibers. Brain Res. 1968 Jul;9(2):374–376. doi: 10.1016/0006-8993(68)90242-4. [DOI] [PubMed] [Google Scholar]
  12. GASSER H. S. Properties of dorsal root unmedullated fibers on the two sides of the ganglion. J Gen Physiol. 1955 May 20;38(5):709–728. doi: 10.1085/jgp.38.5.709. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. IGGO A. Cutaneous mechanoreceptors with afferent C fibres. J Physiol. 1960 Jul;152:337–353. doi: 10.1113/jphysiol.1960.sp006491. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Paintal A. S. Mechanism of stimulation of aortic chemoreceptors by natural stimuli and chemical substances. J Physiol. 1967 Mar;189(1):63–84. doi: 10.1113/jphysiol.1967.sp008155. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Sato A., Fidone S., Eyzaguirre C. Presence of chemoreceptor and baroreceptor C-fibers in the carotid nerve of the cat. Brain Res. 1968 Nov;11(2):459–463. doi: 10.1016/0006-8993(68)90041-3. [DOI] [PubMed] [Google Scholar]

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