Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1994 Oct 1;480(Pt 1):31–43. doi: 10.1113/jphysiol.1994.sp020338

Relaxation, [Ca2+]i and [Mg2+]i during prolonged tetanic stimulation of intact, single fibres from mouse skeletal muscle.

H Westerblad 1, D G Allen 1
PMCID: PMC1155775  PMID: 7853224

Abstract

1. In skeletal muscle there is generally a slowing of relaxation with increasing tetanus duration and it has been suggested that this is due to Ca2+ loading of parvalbumin (PA). To study this we have produced prolonged tetani in intact, single fibres from a mouse foot muscle which contain a high concentration of PA. We measured the rate of tension relaxation and also various aspects of Ca2+ handling. 2. During 'interrupted' tetani (15 repeated cycles of 100 ms with stimulation and 50 ms without) we observed a marked slowing of the relaxation both under control conditions and in acidosis (obtained by increasing the bath CO2 content). This slowing was not accompanied by any reduction of the initial rate of decline of the free myoplasmic Ca2+ concentration ([Ca2+]i), which was measured with indo-1. 3. The functioning of the sarcoplasmic reticulum (SR) pump after tetani of various durations was analysed by plotting d[Ca2+]i/dt vs. [Ca2+]i during the final slow decline of [Ca2+]i after tetani. This analysis showed that the rate of SR Ca2+ pumping after a 1 s tetanus is less than half of that after a 100 ms tetanus. 4. The amplitude of the tail of [Ca2+]i 250 ms into relaxation was measured after tetani of various durations. This amplitude increased with tetanus duration and could be fitted to the sum of one exponential and one linear function. The exponential component increased with a time constant of 0.17 s and probably reflects Ca2+ loading of PA. 5. Ca2+ binding to PA will displace Mg2+ and hence the free myoplasmic concentration of Mg2+ ([Mg2+]i) will increase. To study this we used the fluorescent Mg2+ indicator furaptra. The results showed an increase of [Mg2+]i during prolonged tetani which, after removing the Ca2+ component of the fluorescent signal, amounted to about 0.5 mM. 6. A model of Ca2+ movements and tension production in skeletal muscle was used. The model showed that the increase of the amplitude of [Ca2+]i tails after tetani of various durations can be explained by the combined effect of Ca2+ loading of PA and slowed SR Ca2+ pumping. In contrast to the experimental data, the model predicted a slight reduction of the initial rate of [Ca2+]i decline with increased tetanus duration. 7. In conclusion, we observed a marked slowing of relaxation during prolonged tetanic stimulation. Altered Ca2+ handling, including Ca2+ loading of PA, seems not to be important for this slowing. Thus, the slowing appears to be due to altered cross-bridge kinetics.

Full text

PDF
31

Selected References

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

  1. Baylor S. M., Hollingworth S. Fura-2 calcium transients in frog skeletal muscle fibres. J Physiol. 1988 Sep;403:151–192. doi: 10.1113/jphysiol.1988.sp017244. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Berquin A., Lebacq J. Parvalbumin, labile heat and slowing of relaxation in mouse soleus and extensor digitorum longus muscles. J Physiol. 1992 Jan;445:601–616. doi: 10.1113/jphysiol.1992.sp018942. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Blatter L. A., Wier W. G. Intracellular diffusion, binding, and compartmentalization of the fluorescent calcium indicators indo-1 and fura-2. Biophys J. 1990 Dec;58(6):1491–1499. doi: 10.1016/S0006-3495(90)82494-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Brandt P. W., Cox R. N., Kawai M., Robinson T. Effect of cross-bridge kinetics on apparent Ca2+ sensitivity. J Gen Physiol. 1982 Jun;79(6):997–1016. doi: 10.1085/jgp.79.6.997. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Cannell M. B., Allen D. G. Model of calcium movements during activation in the sarcomere of frog skeletal muscle. Biophys J. 1984 May;45(5):913–925. doi: 10.1016/S0006-3495(84)84238-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Cannell M. B. Effect of tetanus duration on the free calcium during the relaxation of frog skeletal muscle fibres. J Physiol. 1986 Jul;376:203–218. doi: 10.1113/jphysiol.1986.sp016149. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cooke R., Franks K., Luciani G. B., Pate E. The inhibition of rabbit skeletal muscle contraction by hydrogen ions and phosphate. J Physiol. 1988 Jan;395:77–97. doi: 10.1113/jphysiol.1988.sp016909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Curtin N. A. Effects of carbon dioxide and tetanus duration on relaxation of frog skeletal muscle. J Muscle Res Cell Motil. 1986 Jun;7(3):269–275. doi: 10.1007/BF01753560. [DOI] [PubMed] [Google Scholar]
  9. Dantzig J. A., Goldman Y. E., Millar N. C., Lacktis J., Homsher E. Reversal of the cross-bridge force-generating transition by photogeneration of phosphate in rabbit psoas muscle fibres. J Physiol. 1992;451:247–278. doi: 10.1113/jphysiol.1992.sp019163. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Dawson M. J., Gadian D. G., Wilkie D. R. Mechanical relaxation rate and metabolism studied in fatiguing muscle by phosphorus nuclear magnetic resonance. J Physiol. 1980 Feb;299:465–484. doi: 10.1113/jphysiol.1980.sp013137. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Degroot M., Massie B. M., Boska M., Gober J., Miller R. G., Weiner M. W. Dissociation of [H+] from fatigue in human muscle detected by high time resolution 31P-NMR. Muscle Nerve. 1993 Jan;16(1):91–98. doi: 10.1002/mus.880160115. [DOI] [PubMed] [Google Scholar]
  12. Gillis J. M. Relaxation of vertebrate skeletal muscle. A synthesis of the biochemical and physiological approaches. Biochim Biophys Acta. 1985 Jun 3;811(2):97–145. doi: 10.1016/0304-4173(85)90016-3. [DOI] [PubMed] [Google Scholar]
  13. Homsher E., Kean C. J. Skeletal muscle energetics and metabolism. Annu Rev Physiol. 1978;40:93–131. doi: 10.1146/annurev.ph.40.030178.000521. [DOI] [PubMed] [Google Scholar]
  14. Hou T. T., Johnson J. D., Rall J. A. Effect of temperature on relaxation rate and Ca2+, Mg2+ dissociation rates from parvalbumin of frog muscle fibres. J Physiol. 1992 Apr;449:399–410. doi: 10.1113/jphysiol.1992.sp019092. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Irving M., Maylie J., Sizto N. L., Chandler W. K. Simultaneous monitoring of changes in magnesium and calcium concentrations in frog cut twitch fibers containing antipyrylazo III. J Gen Physiol. 1989 Apr;93(4):585–608. doi: 10.1085/jgp.93.4.585. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Jackson A. P., Timmerman M. P., Bagshaw C. R., Ashley C. C. The kinetics of calcium binding to fura-2 and indo-1. FEBS Lett. 1987 May 25;216(1):35–39. doi: 10.1016/0014-5793(87)80752-4. [DOI] [PubMed] [Google Scholar]
  17. Johnson J. D., Charlton S. C., Potter J. D. A fluorescence stopped flow analysis of Ca2+ exchange with troponin C. J Biol Chem. 1979 May 10;254(9):3497–3502. [PubMed] [Google Scholar]
  18. Klein M. G., Kovacs L., Simon B. J., Schneider M. F. Decline of myoplasmic Ca2+, recovery of calcium release and sarcoplasmic Ca2+ pump properties in frog skeletal muscle. J Physiol. 1991 Sep;441:639–671. doi: 10.1113/jphysiol.1991.sp018771. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Konishi M., Hollingworth S., Harkins A. B., Baylor S. M. Myoplasmic calcium transients in intact frog skeletal muscle fibers monitored with the fluorescent indicator furaptra. J Gen Physiol. 1991 Feb;97(2):271–301. doi: 10.1085/jgp.97.2.271. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Lännergren J., Elzinga G., Stienen G. J. Force relaxation, labile heat and parvalbumin content of skeletal muscle fibres of Xenopus laevis. J Physiol. 1993 Apr;463:123–140. doi: 10.1113/jphysiol.1993.sp019587. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Lännergren J., Westerblad H. The temperature dependence of isometric contractions of single, intact fibres dissected from a mouse foot muscle. J Physiol. 1987 Sep;390:285–293. doi: 10.1113/jphysiol.1987.sp016700. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Moore G. A., McConkey D. J., Kass G. E., O'Brien P. J., Orrenius S. 2,5-Di(tert-butyl)-1,4-benzohydroquinone--a novel inhibitor of liver microsomal Ca2+ sequestration. FEBS Lett. 1987 Nov 30;224(2):331–336. doi: 10.1016/0014-5793(87)80479-9. [DOI] [PubMed] [Google Scholar]
  23. Mulligan I. P., Ashley C. C. Rapid relaxation of single frog skeletal muscle fibres following laser flash photolysis of the caged calcium chelator, diazo-2. FEBS Lett. 1989 Sep 11;255(1):196–200. doi: 10.1016/0014-5793(89)81090-7. [DOI] [PubMed] [Google Scholar]
  24. Parkhouse W. S. The effects of ATP, inorganic phosphate, protons, and lactate on isolated myofibrillar ATPase activity. Can J Physiol Pharmacol. 1992 Aug;70(8):1175–1181. doi: 10.1139/y92-163. [DOI] [PubMed] [Google Scholar]
  25. Pechère J. F., Derancourt J., Haiech J. The participation of parvalbumins in the activation-relaxation cycle of vertebrate fast skeletal-muscle. FEBS Lett. 1977 Mar 15;75(1):111–114. doi: 10.1016/0014-5793(77)80064-1. [DOI] [PubMed] [Google Scholar]
  26. Peckham M., Woledge R. C. Labile heat and changes in rate of relaxation of frog muscles. J Physiol. 1986 May;374:123–135. doi: 10.1113/jphysiol.1986.sp016070. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Raju B., Murphy E., Levy L. A., Hall R. D., London R. E. A fluorescent indicator for measuring cytosolic free magnesium. Am J Physiol. 1989 Mar;256(3 Pt 1):C540–C548. doi: 10.1152/ajpcell.1989.256.3.C540. [DOI] [PubMed] [Google Scholar]
  28. Somlyo A. V., Gonzalez-Serratos H. G., Shuman H., McClellan G., Somlyo A. P. Calcium release and ionic changes in the sarcoplasmic reticulum of tetanized muscle: an electron-probe study. J Cell Biol. 1981 Sep;90(3):577–594. doi: 10.1083/jcb.90.3.577. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Spurgeon H. A., duBell W. H., Stern M. D., Sollott S. J., Ziman B. D., Silverman H. S., Capogrossi M. C., Talo A., Lakatta E. G. Cytosolic calcium and myofilaments in single rat cardiac myocytes achieve a dynamic equilibrium during twitch relaxation. J Physiol. 1992 Feb;447:83–102. doi: 10.1113/jphysiol.1992.sp018992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Westerblad H., Allen D. G. Myoplasmic free Mg2+ concentration during repetitive stimulation of single fibres from mouse skeletal muscle. J Physiol. 1992;453:413–434. doi: 10.1113/jphysiol.1992.sp019236. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Westerblad H., Allen D. G. The contribution of [Ca2+]i to the slowing of relaxation in fatigued single fibres from mouse skeletal muscle. J Physiol. 1993 Aug;468:729–740. doi: 10.1113/jphysiol.1993.sp019797. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Westerblad H., Allen D. G. The influence of intracellular pH on contraction, relaxation and [Ca2+]i in intact single fibres from mouse muscle. J Physiol. 1993 Jul;466:611–628. [PMC free article] [PubMed] [Google Scholar]
  33. Westerblad H., Allen D. G. The role of sarcoplasmic reticulum in relaxation of mouse muscle; effects of 2,5-di(tert-butyl)-1,4-benzohydroquinone. J Physiol. 1994 Jan 15;474(2):291–301. doi: 10.1113/jphysiol.1994.sp020022. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Westerblad H., Lännergren J. Slowing of relaxation during fatigue in single mouse muscle fibres. J Physiol. 1991 Mar;434:323–336. doi: 10.1113/jphysiol.1991.sp018472. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Zhu Y., Nosek T. M. Intracellular milieu changes associated with hypoxia impair sarcoplasmic reticulum Ca2+ transport in cardiac muscle. Am J Physiol. 1991 Sep;261(3 Pt 2):H620–H626. doi: 10.1152/ajpheart.1991.261.3.H620. [DOI] [PubMed] [Google Scholar]

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

RESOURCES