Skip to main content
NCBI home page
British Journal of Experimental Pathology logoLink to British Journal of Experimental Pathology
. 1981 Dec;62(6):600–605.

Quantitative studies on the numerical frequency of myonuclei in the muscles of exercised rats: evidence against the occurrence of fibre-splitting.

N T James, M Cabric
PMCID: PMC2041721  PMID: 7326216

Abstract

The histological changes associated with exercise-induced muscular hypertrophy have variously been interpreted as due to fibre-splitting or satellite-cell activity. If due to fibre-splitting, than a marked fall in the number of nuclei per unit volume of muscle must occur. To see if this is the case, we have examined post-mortem specimens of extensor digitorum longus muscles in rats exercised by swimming for up to 30 min twice daily for 35 days. The mean cross-sectional area of muscle fibres was unaltered by exercise but mean length of capillary per unit volume of muscle was increased by 55% and number of nuclei per unit volume of muscle by 30%, both changes being significant. Mean nuclear volume increased by approximately 75%. Thus the muscles did adapt to exercise and new myonuclei were formed, contrary to expectations if fibre-splitting were the essential change. In this study the fibres seemed not to have increased in size and further studies, perhaps using autoradiographic analysis of tritiated thymidine-labelled satellite-cell nuclei, are needed to clarify the precise mechanisms involved.

Full text

PDF
600

Selected References

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

  1. ALDER A. B., CRAWFORD G. N., EDWARDS R. G. The effect of limitation of movement on longitudinal muscle growth. Proc R Soc Lond B Biol Sci. 1959 Sep 1;150:554–562. doi: 10.1098/rspb.1959.0042. [DOI] [PubMed] [Google Scholar]
  2. Atherton G. W., James N. T., Mahon M. Studies on muscle fibre splitting in skeletal muscle. Experientia. 1981 Mar 15;37(3):308–310. doi: 10.1007/BF01991672. [DOI] [PubMed] [Google Scholar]
  3. Cruz Orive L. M. On the estimation of particle number. J Microsc. 1980 Sep;120(Pt 1):15–27. doi: 10.1111/j.1365-2818.1980.tb04116.x. [DOI] [PubMed] [Google Scholar]
  4. Edgerton V. R. Morphology and histochemistry of the soleus muscle from normal and exercised rats. Am J Anat. 1970 Jan;127(1):81–87. doi: 10.1002/aja.1001270107. [DOI] [PubMed] [Google Scholar]
  5. Hall-Craggs E. C. The significance of longitudinal fibre division in skeletal muscle. J Neurol Sci. 1972;15(1):27–33. doi: 10.1016/0022-510x(72)90119-0. [DOI] [PubMed] [Google Scholar]
  6. Ho K. W., Roy R. R., Tweedle C. D., Heusner W. W., Van Huss W. D., Carrow R. E. Skeletal muscle fiber splitting with weight-lifting exercise in rats. Am J Anat. 1980 Apr;157(4):433–440. doi: 10.1002/aja.1001570410. [DOI] [PubMed] [Google Scholar]
  7. James N. T. A stereological analysis of capillaries in normal and hypertrophic muscle. J Morphol. 1981 Apr;168(1):43–49. doi: 10.1002/jmor.1051680106. [DOI] [PubMed] [Google Scholar]
  8. James N. T. Compensatory hypertrophy in the extensor digitorum longus muscle of the rat. J Anat. 1973 Oct;116(Pt 1):57–65. [PMC free article] [PubMed] [Google Scholar]
  9. James N. T., Meek G. A. Stereological analyses of the structure of mitochondria in pigeon skeletal muscle. Cell Tissue Res. 1979 Nov;202(3):493–503. doi: 10.1007/BF00220440. [DOI] [PubMed] [Google Scholar]
  10. James N. T. Studies on the responses of different types of muscle fibre during surgically induced compensatory hypertrophy. J Anat. 1979 Dec;129(Pt 4):769–776. [PMC free article] [PubMed] [Google Scholar]
  11. MAURO A. Satellite cell of skeletal muscle fibers. J Biophys Biochem Cytol. 1961 Feb;9:493–495. doi: 10.1083/jcb.9.2.493. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Müller W. Subsarcolemmal mitochondria and capillarization of soleus muscle fibers in young rats subjected to an endurance training. A morphometric study of semithin sections. Cell Tissue Res. 1976 Nov 10;174(3):367–389. doi: 10.1007/BF00220682. [DOI] [PubMed] [Google Scholar]
  13. Müller W., Vogell L. Temporal progress of muscle adaptation to endurance training in hind limb muscles of young rats. A histochemical and morphometrical study. Cell Tissue Res. 1974;156(1):61–87. doi: 10.1007/BF00220102. [DOI] [PubMed] [Google Scholar]
  14. Reger J. F., Craig A. S. Studies on the fine structure of muscle fibers and associated satellite cells in hypertrophic human deltoid muscle. Anat Rec. 1968 Dec;162(4):483–500. doi: 10.1002/ar.1091620410. [DOI] [PubMed] [Google Scholar]
  15. Reitsma W. Skeletal muscle hypertrophy after heavy exercise in rats with surgically reduced muscle function. Am J Phys Med. 1969 Oct;48(5):237–258. [PubMed] [Google Scholar]
  16. Reitsma W. Some structural changes in skeletal muscles of the rat after intensive training. Acta Morphol Neerl Scand. 1970;7(3):229–245. [PubMed] [Google Scholar]
  17. Rowe R. W., Goldspink G. Surgically induced hypertrophy in skeletal muscles of the laboratory mouse. Anat Rec. 1968 May;161(1):69–75. doi: 10.1002/ar.1091610107. [DOI] [PubMed] [Google Scholar]
  18. Schwartz M. S., Sargeant M., Swash M. Longitudinal fibre splitting in neurogenic muscular disorders--its relation to the pathogenesis of "myopathic" change. Brain. 1976 Dec;99(4):617–636. doi: 10.1093/brain/99.4.617. [DOI] [PubMed] [Google Scholar]
  19. Sola O. M., Christensen D. L., Martin A. W. Hypertrophy and hyperplasia of adult chicken anterior latissimus dorsi muscles following stretch with and without denervation. Exp Neurol. 1973 Oct;41(1):76–100. doi: 10.1016/0014-4886(73)90182-9. [DOI] [PubMed] [Google Scholar]
  20. Teräväinen H. Satellite cells of striated muscle after compression injury so slight as not to cause degeneration of the muscle fibres. Z Zellforsch Mikrosk Anat. 1970;103(3):320–327. doi: 10.1007/BF00335276. [DOI] [PubMed] [Google Scholar]
  21. VAN LINGE B. The response of muscle to strenuous exercise. An experimental study in the rat. J Bone Joint Surg Br. 1962 Aug;44-B:711–721. doi: 10.1302/0301-620X.44B3.711. [DOI] [PubMed] [Google Scholar]
  22. Vaughan H. S., Goldspink G. Fibre number and fibre size in a surgically overloaded muscle. J Anat. 1979 Sep;129(Pt 2):293–303. [PMC free article] [PubMed] [Google Scholar]
  23. Wilson A. B., Duncan L., Wrottesley M. G., Fell B. F. Hypertrophy of the internal oblique abdominal muscle of ewes bred intensively. J Comp Pathol. 1978 Jul;88(3):345–363. doi: 10.1016/0021-9975(78)90039-7. [DOI] [PubMed] [Google Scholar]

Articles from British journal of experimental pathology are provided here courtesy of Wiley

RESOURCES