Skip to main content
The Journal of Physiology logoLink to The Journal of Physiology
. 1986 Jun;375:391–401. doi: 10.1113/jphysiol.1986.sp016123

Contractile activation in myotomes from developing larvae of Xenopus laevis.

C L Huang
PMCID: PMC1182765  PMID: 3795064

Abstract

Contractile activation in response to application of different perfusing solutions was observed in developing myotomes from larvae of Xenopus laevis. Contractures resulted from treatment with isotonic solutions containing high K+ concentrations in myotomes from embryos from stage 24 onwards. These developed over 5-10 s and inactivated over 20-30 s. Contractures persisted in curarized preparations. The applied K+ concentrations at the estimated mechanical threshold in embryos at stages 26 and 34 were about 30 and 20 mM respectively. Maximum activity was achieved at K+ concentrations of 78 and 48 mM respectively. The lyotropic ion thiocyanate (10 mM) potentiated K+ contractures, and shifted the threshold K+ concentration to lower values. Contractures persisted in the presence of 3 mM-Mn2+ and in Ca2+-free solutions, with unaltered mechanical thresholds. K+ contractures were reversibly abolished by 2 mM-tetracaine. Comparisons of resting potentials in 3 and 20 mM-K+ confirmed that the resting potential remained sensitive to external K+ concentration, whether in control, tetracaine-containing, or low-Ca2+ bathing solutions. Caffeine (10-20 mM) caused sustained contractures from stage 24 onwards. Caffeine sensitivity was greatest at stages 26-28, then appeared to decline at stages 33-36. These observations suggest that mechanisms for excitation-contraction coupling develop in Xenopus embryos at the same time as do completed sarcomeres, close to stage 24. Activation of contraction then assumes the adult pattern, involving voltage-dependent release of the intracellular store of activator, independent of entry of extracellular Ca2+.

Full text

PDF
391

Selected References

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

  1. ADRIAN R. H. The effect of internal and external potassium concentration on the membrane potential of frog muscle. J Physiol. 1956 Sep 27;133(3):631–658. doi: 10.1113/jphysiol.1956.sp005615. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Adrian R. H., Chandler W. K., Hodgkin A. L. The kinetics of mechanical activation in frog muscle. J Physiol. 1969 Sep;204(1):207–230. doi: 10.1113/jphysiol.1969.sp008909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Armstrong D. L., Turin L., Warner A. E. Muscle activity and the loss of electrical coupling between striated muscle cells in Xenopus embryos. J Neurosci. 1983 Jul;3(7):1414–1421. doi: 10.1523/JNEUROSCI.03-07-01414.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Ashley C. C., Ridgway E. B. On the relationships between membrane potential, calcium transient and tension in single barnacle muscle fibres. J Physiol. 1970 Jul;209(1):105–130. doi: 10.1113/jphysiol.1970.sp009158. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Baccaglini P. I., Spitzer N. C. Developmental changes in the inward current of the action potential of Rohon-Beard neurones. J Physiol. 1977 Sep;271(1):93–117. doi: 10.1113/jphysiol.1977.sp011992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Beaty G. N., Stefani E. Calcium dependent electrical activity in twitch muscle fibres of the frog. Proc R Soc Lond B Biol Sci. 1976 Aug 27;194(1114):141–150. doi: 10.1098/rspb.1976.0070. [DOI] [PubMed] [Google Scholar]
  7. Blackshaw S. E., Warner A. E. Low resistance junctions between mesoderm cells during development of trunk muscles. J Physiol. 1976 Feb;255(1):209–230. doi: 10.1113/jphysiol.1976.sp011276. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Caputo C., Fernandez de Bolaños P. Membrane potential, contractile activation and relaxation rates in voltage clamped short muscle fibres of the frog. J Physiol. 1979 Apr;289:175–189. doi: 10.1113/jphysiol.1979.sp012731. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Caputo C. The effect of caffeine and tetracaine on the time course of potassium contractures of single muscle fibres. J Physiol. 1976 Feb;255(1):191–207. doi: 10.1113/jphysiol.1976.sp011275. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Caputo C. The time course of potassium contractures of single muscle fibres. J Physiol. 1972 Jun;223(2):483–505. doi: 10.1113/jphysiol.1972.sp009859. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. HODGKIN A. L., HOROWICZ P. Potassium contractures in single muscle fibres. J Physiol. 1960 Sep;153:386–403. doi: 10.1113/jphysiol.1960.sp006541. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. HODGKIN A. L., HOROWICZ P. The effect of nitrate and other anions on the mechanical response of single muscle fibres. J Physiol. 1960 Sep;153:404–412. doi: 10.1113/jphysiol.1960.sp006542. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hamilton L. The formation of somites in Xenopus. J Embryol Exp Morphol. 1969 Sep;22(2):253–264. [PubMed] [Google Scholar]
  14. Huang C. L. Dielectric components of charge movements in skeletal muscle. J Physiol. 1981;313:187–205. doi: 10.1113/jphysiol.1981.sp013658. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Hui C. S. Pharmacological studies of charge movement in frog skeletal muscle. J Physiol. 1983 Apr;337:509–529. doi: 10.1113/jphysiol.1983.sp014639. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Kano M. Development of excitability in embryonic chick skeletal muscle cells. J Cell Physiol. 1975 Dec;86(3 Pt 1):503–510. doi: 10.1002/jcp.1040860307. [DOI] [PubMed] [Google Scholar]
  17. Lüttgau H. C., Oetliker H. The action of caffeine on the activation of the contractile mechanism in straited muscle fibres. J Physiol. 1968 Jan;194(1):51–74. doi: 10.1113/jphysiol.1968.sp008394. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Lüttgau H. C., Spiecker W. The effects of calcium deprivation upon mechanical and electrophysiological parameters in skeletal muscle fibres of the frog. J Physiol. 1979 Nov;296:411–429. doi: 10.1113/jphysiol.1979.sp013013. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Schneider M. F., Chandler W. K. Voltage dependent charge movement of skeletal muscle: a possible step in excitation-contraction coupling. Nature. 1973 Mar 23;242(5395):244–246. doi: 10.1038/242244a0. [DOI] [PubMed] [Google Scholar]
  20. Spitzer N. C. The ionic basis of the resting potential and a slow depolarizing response in Rohon-Beard neurones of Xenopus tadpoles. J Physiol. 1976 Feb;255(1):105–135. doi: 10.1113/jphysiol.1976.sp011272. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Stanfield P. R. A calcium dependent inward current in frog skeletal muscle fibres. Pflugers Arch. 1977 Apr 25;368(3):267–270. doi: 10.1007/BF00585206. [DOI] [PubMed] [Google Scholar]
  22. Vergara J., Caputo C. Effects of tetracaine on charge movements and calcium signals in frog skeletal muscle fibers. Proc Natl Acad Sci U S A. 1983 Mar;80(5):1477–1481. doi: 10.1073/pnas.80.5.1477. [DOI] [PMC free article] [PubMed] [Google Scholar]

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

RESOURCES