Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1992 Feb;447:549–562. doi: 10.1113/jphysiol.1992.sp019017

Changes in R-R interval at the start of muscle contraction in the decerebrate cat.

S E McMahon 1, P N McWilliam 1
PMCID: PMC1176051  PMID: 1593459

Abstract

1. The effect on R-R interval of a brief hindlimb contraction, elicited by electrical stimulation of L7 ventral roots, was investigated in decerebrate cats. The first series of experiments was performed at both low and high carotid sinus pressure to vary the level of vagal tone. When carotid sinus pressure was elevated to increase vagal tone, contraction commenced 1 s later. 2. The change in R-R interval at low carotid sinus pressure was expressed as the difference between the mean of the five R-R intervals immediately preceding contraction and the mean of the last five R-R intervals at the end of a 5 s contraction. At high carotid sinus pressure, the change was expressed as the difference between the mean of the last five R-R intervals at the end of a 5 s contraction and the mean of five R-R intervals at an equivalent time after raising pressure alone. 3. Hindlimb contraction at low carotid sinus pressure produced a significant reduction in R-R interval from 359 +/- 25 (mean +/- S.E.M. n = 8) to 336 +/- 24 ms (P less than 0.005). At high carotid sinus pressure the response was enhanced with contraction producing a reduction in R-R interval from 474 +/- 45 to 419 +/- 47 ms (P less than 0.001). 4. The shortening of R-R interval produced by hindlimb contraction at high carotid sinus pressure, 55 +/- 8 ms, was significantly greater than that observed at low sinus pressure, 23 +/- 5 ms (P less than 0.001, n = 8, paired t test). This pattern of response was also seen at stimulation frequencies as low as 10 Hz. 5. In a second series of experiments, designed to determine the latency of the cardiac acceleration, the minimum latency between the onset of L7 ventral root stimulation and the end of the first shortened R-R interval was 687 +/- 29 ms (n = 5). 6. Atropine (0.4 mg kg-1, I.V.) prevented a 5 s contraction from producing any change in R-R interval. 7. These results indicate that afferent information originating from receptors in contracting muscles is responsible for producing an immediate shortening of R-R interval, which is mediated by vagal withdrawal. The possibility that the shortening of R-R interval at the start of contraction is linked to a reduction in arterial baroreceptor reflex sensitivity, possibly via inhibitory effects on neurones forming the central pathway of the baroreceptor reflex, is discussed.

Full text

PDF
549

Selected References

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

  1. Anderson I. D., Little R. A., Irving M. H. An effect of trauma on human cardiovascular control: baroreflex suppression. J Trauma. 1990 Aug;30(8):974–982. doi: 10.1097/00005373-199008000-00005. [DOI] [PubMed] [Google Scholar]
  2. Bennett J. A., McWilliam P. N., Shepheard S. L. A gamma-aminobutyric-acid-mediated inhibition of neurones in the nucleus tractus solitarius of the cat. J Physiol. 1987 Nov;392:417–430. doi: 10.1113/jphysiol.1987.sp016788. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bevegård B. S., Shepherd J. T. Circulatory effects of stimulating the carotid arterial stretch receptors in man at rest and during exercise. J Clin Invest. 1966 Jan;45(1):132–142. doi: 10.1172/JCI105317. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Coote J. H., Dodds W. N. The baroreceptor reflex and the cardiovascular changes associated with sustained muscular contraction in the cat. Pflugers Arch. 1976 May 12;363(2):167–173. doi: 10.1007/BF01062286. [DOI] [PubMed] [Google Scholar]
  5. Coote J. H., Hilton S. M., Perez-Gonzalez J. F. The reflex nature of the pressor response to muscular exercise. J Physiol. 1971 Jul;215(3):789–804. doi: 10.1113/jphysiol.1971.sp009498. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Diepstra G., Gonyea W., Mitchell J. H. Cardiovascular response to static exercise during selective autonomic blockade in the conscious cat. Circ Res. 1980 Oct;47(4):530–535. doi: 10.1161/01.res.47.4.530. [DOI] [PubMed] [Google Scholar]
  7. Eckberg D. L., Wallin B. G. Isometric exercise modifies autonomic baroreflex responses in humans. J Appl Physiol (1985) 1987 Dec;63(6):2325–2330. doi: 10.1152/jappl.1987.63.6.2325. [DOI] [PubMed] [Google Scholar]
  8. Fisher M. L., Nutter D. O. Cardiovascular reflex adjustments to static muscular contractions in the canine hindlimb. Am J Physiol. 1974 Mar;226(3):648–655. doi: 10.1152/ajplegacy.1974.226.3.648. [DOI] [PubMed] [Google Scholar]
  9. Freyschuss U. Elicitation of heart rate and blood pressure increase on muscle contraction. J Appl Physiol. 1970 Jun;28(6):758–761. doi: 10.1152/jappl.1970.28.6.758. [DOI] [PubMed] [Google Scholar]
  10. Gelsema A. J., De Groot G., Bouman L. N. Instantaneous cardiac acceleration in the cat elicited by peripheral nerve stimulation. J Appl Physiol Respir Environ Exerc Physiol. 1983 Sep;55(3):703–710. doi: 10.1152/jappl.1983.55.3.703. [DOI] [PubMed] [Google Scholar]
  11. Hollander A. P., Bouman L. N. Cardiac acceleration in man elicited by a muscle-heart reflex. J Appl Physiol. 1975 Feb;38(2):272–278. doi: 10.1152/jappl.1975.38.2.272. [DOI] [PubMed] [Google Scholar]
  12. Iwamoto G. A., Mitchell J. H., Mizuno M., Secher N. H. Cardiovascular responses at the onset of exercise with partial neuromuscular blockade in cat and man. J Physiol. 1987 Mar;384:39–47. doi: 10.1113/jphysiol.1987.sp016442. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Krogh A., Lindhard J. The regulation of respiration and circulation during the initial stages of muscular work. J Physiol. 1913 Oct 17;47(1-2):112–136. doi: 10.1113/jphysiol.1913.sp001616. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Lassen A., Mitchell J. H., Reeves D. R., Jr, Rogers H. B., Secher N. H. Cardiovascular responses to brief static contractions in man with topical nervous blockade. J Physiol. 1989 Feb;409:333–341. doi: 10.1113/jphysiol.1989.sp017500. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Leonard B., Mitchell J. H., Mizuno M., Rube N., Saltin B., Secher N. H. Partial neuromuscular blockade and cardiovascular responses to static exercise in man. J Physiol. 1985 Feb;359:365–379. doi: 10.1113/jphysiol.1985.sp015590. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Lipski J., McAllen R. M., Spyer K. M. The sinus nerve and baroreceptor input to the medulla of the cat. J Physiol. 1975 Sep;251(1):61–78. doi: 10.1113/jphysiol.1975.sp011081. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Lorentzon R., Larsson S. E. Intestinal absorption and tissue retention of cadmium and calcium in normal adult rats and rats given an active metabolite of vitamin D (1,25-dihydroxycholecalciferol). Clin Sci Mol Med. 1978 Aug;55(2):195–198. doi: 10.1042/cs0550195. [DOI] [PubMed] [Google Scholar]
  18. Mancia G., Iannos J., Jamieson G. G., Lawrence R. H., Sharman P. R., Ludbrook J. Effect of isometric hand-grip exercise on the carotid sinus baroreceptor reflex in man. Clin Sci Mol Med. 1978 Jan;54(1):33–37. doi: 10.1042/cs0540033. [DOI] [PubMed] [Google Scholar]
  19. Matsukawa K., Mitchell J. H., Wall P. T., Wilson L. B. The effect of static exercise on renal sympathetic nerve activity in conscious cats. J Physiol. 1991 Mar;434:453–467. doi: 10.1113/jphysiol.1991.sp018480. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. McAllen R. M., Spyer K. M. The location of cardiac vagal preganglionic motoneurones in the medulla of the cat. J Physiol. 1976 Jun;258(1):187–204. doi: 10.1113/jphysiol.1976.sp011414. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. McCloskey D. I., Mitchell J. H. Reflex cardiovascular and respiratory responses originating in exercising muscle. J Physiol. 1972 Jul;224(1):173–186. doi: 10.1113/jphysiol.1972.sp009887. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. McWilliam P. N., Shepheard S. L. A GABA-mediated inhibition of neurones in the nucleus tractus solitarius of the cat that respond to electrical stimulation of the carotid sinus nerve. Neurosci Lett. 1988 Dec 5;94(3):321–326. doi: 10.1016/0304-3940(88)90038-9. [DOI] [PubMed] [Google Scholar]
  23. McWilliam P. N., Yang T., Chen L. X. Changes in the baroreceptor reflex at the start of muscle contraction in the decerebrate cat. J Physiol. 1991 May;436:549–558. doi: 10.1113/jphysiol.1991.sp018566. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. McWilliam P. N., Yang T. Inhibition of cardiac vagal component of baroreflex by group III and IV afferents. Am J Physiol. 1991 Mar;260(3 Pt 2):H730–H734. doi: 10.1152/ajpheart.1991.260.3.H730. [DOI] [PubMed] [Google Scholar]
  25. Mitchell J. H., Reardon W. C., McCloskey D. I. Reflex effects on circulation and respiration from contracting skeletal muscle. Am J Physiol. 1977 Sep;233(3):H374–H378. doi: 10.1152/ajpheart.1977.233.3.H374. [DOI] [PubMed] [Google Scholar]
  26. Parker P., Celler B. G., Potter E. K., McCloskey D. I. Vagal stimulation and cardiac slowing. J Auton Nerv Syst. 1984 Sep;11(2):226–231. doi: 10.1016/0165-1838(84)90080-8. [DOI] [PubMed] [Google Scholar]
  27. Secher N. H. Heart rate at the onset of static exercise in man with partial neuromuscular blockade. J Physiol. 1985 Nov;368:481–490. doi: 10.1113/jphysiol.1985.sp015870. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Streatfeild K. A., Davidson N. S., McCloskey D. I. Muscular reflex and baroreflex influences on heart rate during isometric contractions. Cardiovasc Res. 1977 Mar;11(2):87–93. doi: 10.1093/cvr/11.2.87. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES