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. 1984 Feb;81(2):351–360. doi: 10.1111/j.1476-5381.1984.tb10086.x

The action of dantrolene sodium on individual fast and slow motor units of the rat anaesthetized with urethane.

G C Leslie, N J Part
PMCID: PMC1986876  PMID: 6704595

Abstract

Rats, anaesthetized with urethane, were injected intravenously with dantrolene sodium in a vehicle of 5% mannitol taken to pH 10 with NaOH. The muscle relaxant action of dantrolene sodium was measured from the contractions of individual motor units of the extensor digitorum longus (EDL), soleus (SOL) and segmental tail (ST) muscles. Data were also collected from their parent whole muscle preparations. The depressant action of dantrolene sodium on the percentage-normalized amplitude of contraction of the individual motor units was greater than its effect on the whole muscle twitch amplitude, in all three muscles. The twitch amplitude of fast contracting motor units was significantly more reduced (P less than 0.001) by dantrolene sodium than was that of slow contracting motor units. Dantrolene sodium reduced the contraction time of all motor units. The effect of the drug on half-relaxation time varied within and between groups of motor units studied. The drug was confirmed to have a greater depressant action on the twitch contraction than on the fused tetanus of whole muscle. This was true also for single motor units. With tetanic stimulation the effect of dantrolene sodium was also dependent upon the motor unit type, fast or slow. A maximum depression of contractile tension occurred at a stimulation frequency of 64 Hz for fast EDL motor units whereas the maximum depression for ST slow units, the slowest units tested, was at a stimulation frequency of 14 Hz.

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Selected References

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

  1. Andrew B. L., Part N. J. Properties of fast and slow motor units in hind limb and tail muscles of the rat. Q J Exp Physiol Cogn Med Sci. 1972 Apr;57(2):213–225. doi: 10.1113/expphysiol.1972.sp002151. [DOI] [PubMed] [Google Scholar]
  2. Bowman W. C., Houston J., Khan H. H., Rodger I. W. Effects of dantrolene sodium on respiratory and other muscles and on respiratory parameters in the anaesthetised cat. Eur J Pharmacol. 1979 May 1;55(3):293–303. doi: 10.1016/0014-2999(79)90197-3. [DOI] [PubMed] [Google Scholar]
  3. Close R. Properties of motor units in fast and slow skeletal muscles of the rat. J Physiol. 1967 Nov;193(1):45–55. doi: 10.1113/jphysiol.1967.sp008342. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Ellis K. O., Butterfield J. L., Wessels F. L., Carpenter J. F. A comparison of skeletal, cardiac, and smooth muscle actions of dantrolene sodium--a skeletal muscle relaxant. Arch Int Pharmacodyn Ther. 1976 Nov;224(1):118–132. [PubMed] [Google Scholar]
  5. Ellis K. O., Carpenter J. F. Studies on the mechanism of action of dantrolene sodium. A skeletal muscle relaxant. Naunyn Schmiedebergs Arch Pharmacol. 1972;275(1):83–94. doi: 10.1007/BF00505069. [DOI] [PubMed] [Google Scholar]
  6. Ellis K. O., Castellion A. W., Honkomp L. J., Wessels F. L., Carpenter J. E., Halliday R. P. Dantrolene, a direct acting skeletal muscle relaxant. J Pharm Sci. 1973 Jun;62(6):948–951. doi: 10.1002/jps.2600620619. [DOI] [PubMed] [Google Scholar]
  7. Jami L., Murthy K. S., Petit J., Zytnicki D. Action of dantrolene sodium on single motor units of cat muscle in vivo. Brain Res. 1983 Feb 21;261(2):285–294. doi: 10.1016/0006-8993(83)90631-5. [DOI] [PubMed] [Google Scholar]
  8. Kugelberg E. Histochemical composition, contraction speed and fatiguability of rat soleus motor units. J Neurol Sci. 1973 Oct;20(2):177–198. doi: 10.1016/0022-510x(73)90029-4. [DOI] [PubMed] [Google Scholar]
  9. Leslie G. C., Part N. J. The action of dantrolene sodium on rat fast and slow muscle in vivo. Br J Pharmacol. 1981 Apr;72(4):665–672. doi: 10.1111/j.1476-5381.1981.tb09147.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Mai J., Pedersen E. Mode of action of dantrolene sodium in spasticity. Acta Neurol Scand. 1979 Jun;59(6):309–316. doi: 10.1111/j.1600-0404.1979.tb02941.x. [DOI] [PubMed] [Google Scholar]
  11. Nott M. W., Bowman W. C. Actions of dantrolene sodium on contractions of the tibialis anterior and soleus muscles of cats under chloralose anaesthesia. Clin Exp Pharmacol Physiol. 1974 Mar-Apr;1(2):113–122. doi: 10.1111/j.1440-1681.1974.tb00532.x. [DOI] [PubMed] [Google Scholar]
  12. Pullen A. H. The distribution and relative sized of fibre types in the extensor digitorum longus and soleus muscles of the adult rat. J Anat. 1977 Apr;123(Pt 2):467–486. [PMC free article] [PubMed] [Google Scholar]
  13. Putney J. W., Biancri C. P. Site of action of dantrolene in frog sartorius muscle. J Pharmacol Exp Ther. 1974 Apr;189(1):202–212. [PubMed] [Google Scholar]
  14. STEIN J. M., PADYKULA H. A. Histochemical classification of individual skeletal muscle fibers of the rat. Am J Anat. 1962 Mar;110:103–123. doi: 10.1002/aja.1001100203. [DOI] [PubMed] [Google Scholar]
  15. Schmalbruch H., Kamieniecka Z. Histochemical fiber typing and staining intensity in cat and rat muscles. J Histochem Cytochem. 1975 Jun;23(6):395–401. doi: 10.1177/23.6.125297. [DOI] [PubMed] [Google Scholar]
  16. Stephenson D. G., Williams D. A. Calcium-activated force responses in fast- and slow-twitch skinned muscle fibres of the rat at different temperatures. J Physiol. 1981 Aug;317:281–302. doi: 10.1113/jphysiol.1981.sp013825. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Van Winkle W. B. Calcium release from skeletal muscle sarcoplasmic reticulum: site of action of dantrolene sodium. Science. 1976 Sep 17;193(4258):1130–1131. doi: 10.1126/science.959824. [DOI] [PubMed] [Google Scholar]

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