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. 1981 Apr 1;77(4):419–443. doi: 10.1085/jgp.77.4.419

Ca2+ dependence of stimulated 45Ca efflux in skinned muscle fibers

PMCID: PMC2215418  PMID: 6264018

Abstract

Stimulation of sarcoplasmic reticulum Ca release by Mg reduction of caffeine was studied in situ, to characterize further the Ca2+ dependence observed previously with stimulation by Cl ion. 45Ca efflux and isometric force were measured simultaneously at 19 degrees C in frog skeletal muscle fibers skinned by microdissection; EGTA was added to chelate myofilament space Ca either before or after the stimulus. Both Mg2+ reduction (20 or 110 microM to 4 microM) and caffeine (5 mM) induced large force responses and 45Ca release, which were inhibited by pretreatment with 5 mM EGTA. In the case of Mg reduction, residual efflux stimulation was undetectable, and 45Ca efflux in EGTA at 4 microM Mg2+ was not significantly increased. Residual caffeine stimulation at 20 microM Mg2+ was substantial and was reduced further in increased EGTA (10 mM); at 600 microM Mg2+, residual stimulation in 5 mM EGTA was undetectable. Caffeine appears to initiate a small Ca2+- insensitive efflux that produces a large Ca2+-dependent efflux. Additional experiments suggested that caffeine also inhibited influx. The results suggest that stimulated efflux is mediated mainly or entirely by a channel controlled by an intrinsic Ca2+ receptor, which responds to local [Ca2+] in or near the channel. Receptor affinity for Ca2+ probably is influenced by Mg2+, but inhibition is weak unless local [Ca2+] is very low.

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Selected References

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

  1. Blinks J. R., Rüdel R., Taylor S. R. Calcium transients in isolated amphibian skeletal muscle fibres: detection with aequorin. J Physiol. 1978 Apr;277:291–323. doi: 10.1113/jphysiol.1978.sp012273. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. 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]
  3. Carvalho A. P., Leo B. Effects of ATP on the interaction of Ca++, Mg++, and K+ with fragmented sarcoplasmic reticulum isolated from rabbit skeletal muscle. J Gen Physiol. 1967 May;50(5):1327–1352. doi: 10.1085/jgp.50.5.1327. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Costantin L. L., Podolsky R. J. Depolarization of the internal membrane system in the activation of frog skeletal muscle. J Gen Physiol. 1967 May;50(5):1101–1124. doi: 10.1085/jgp.50.5.1101. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Donaldson S. K., Kerrick W. G. Characterization of the effects of Mg2+ on Ca2+- and Sr2+-activated tension generation of skinned skeletal muscle fibers. J Gen Physiol. 1975 Oct;66(4):427–444. doi: 10.1085/jgp.66.4.427. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Endo M. Calcium release from the sarcoplasmic reticulum. Physiol Rev. 1977 Jan;57(1):71–108. doi: 10.1152/physrev.1977.57.1.71. [DOI] [PubMed] [Google Scholar]
  7. Fairhurst A. S., Hasselbach W. Calcium efflux from a heavy sarcotubular fraction. Effects of ryanodine, caffeine and magnesium. Eur J Biochem. 1970 Apr;13(3):504–509. doi: 10.1111/j.1432-1033.1970.tb00953.x. [DOI] [PubMed] [Google Scholar]
  8. Ford L. E., Podolsky R. J. Calcium uptake and force development by skinned muscle fibres in EGTA buffered solutions. J Physiol. 1972 May;223(1):1–19. doi: 10.1113/jphysiol.1972.sp009830. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Ford L. E., Podolsky R. J. Intracellular calcium movements in skinned muscle fibres. J Physiol. 1972 May;223(1):21–33. doi: 10.1113/jphysiol.1972.sp009831. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Frank J. S., Winegrad S. Effect of muscle length on 45Ca efflux in resting and contracting skeletal muscle. Am J Physiol. 1976 Aug;231(2):555–559. doi: 10.1152/ajplegacy.1976.231.2.555. [DOI] [PubMed] [Google Scholar]
  11. Godt R. E. Calcium-activated tension of skinned muscle fibers of the frog. Dependence on magnesium adenosine triphosphate concentration. J Gen Physiol. 1974 Jun;63(6):722–739. doi: 10.1085/jgp.63.6.722. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Howell J. N. A lesion of the transverse tubules of skeletal muscle. J Physiol. 1969 May;201(3):515–533. doi: 10.1113/jphysiol.1969.sp008770. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Katz A. M., Repke D. I., Fudyma G., Shigekawa M. Control of calcium efflux from sarcoplasmic reticulum vesicles by external calcium. J Biol Chem. 1977 Jun 25;252(12):4210–4214. [PubMed] [Google Scholar]
  14. Kovács L., Ríos E., Schneider M. F. Calcium transients and intramembrane charge movement in skeletal muscle fibres. Nature. 1979 May 31;279(5712):391–396. doi: 10.1038/279391a0. [DOI] [PubMed] [Google Scholar]
  15. 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]
  16. MacLennan D. H., Holland P. C. Calcium transport in sarcoplasmic reticulum. Annu Rev Biophys Bioeng. 1975;4(00):377–404. doi: 10.1146/annurev.bb.04.060175.002113. [DOI] [PubMed] [Google Scholar]
  17. Moisescu D. G., Thieleczek R. Calcium and strontium concentration changes within skinned muscle preparations following a change in the external bathing solution. J Physiol. 1978 Feb;275:241–262. doi: 10.1113/jphysiol.1978.sp012188. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Ogawa Y., Ebashi S. Ca-releasing action of beta, gamma-methylene adenosine triphosphate on fragmented sarcoplasmic reticulum. J Biochem. 1976 Nov;80(5):1149–1157. doi: 10.1093/oxfordjournals.jbchem.a131370. [DOI] [PubMed] [Google Scholar]
  19. Stephenson E. W., Podolsky R. J. Influence of magnesium on chloride-induced calcium release in skinned muscle fibers. J Gen Physiol. 1977 Jan;69(1):17–35. doi: 10.1085/jgp.69.1.17. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Stephenson E. W., Podolsky R. J. Influence of magnesium on chloride-induced calcium release in skinned muscle fibers. J Gen Physiol. 1977 Jan;69(1):17–35. doi: 10.1085/jgp.69.1.17. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Stephenson E. W., Podolsky R. J. Regulation by magnesium of intracellular calcium movement in skinned muscle fibers. J Gen Physiol. 1977 Jan;69(1):1–16. doi: 10.1085/jgp.69.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Stephenson E. W., Podolsky R. J. The regulation of calcium in skeletal muscle. Ann N Y Acad Sci. 1978 Apr 28;307:462–476. doi: 10.1111/j.1749-6632.1978.tb41976.x. [DOI] [PubMed] [Google Scholar]
  23. Stephenson E. W. Properties of chloride-stimulated 45Ca flux in skinned muscle fibers. J Gen Physiol. 1978 Apr;71(4):411–430. doi: 10.1085/jgp.71.4.411. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Tada M., Yamamoto T., Tonomura Y. Molecular mechanism of active calcium transport by sarcoplasmic reticulum. Physiol Rev. 1978 Jan;58(1):1–79. doi: 10.1152/physrev.1978.58.1.1. [DOI] [PubMed] [Google Scholar]
  25. Weber A., Herz R. The relationship between caffeine contracture of intact muscle and the effect of caffeine on reticulum. J Gen Physiol. 1968 Nov;52(5):750–759. doi: 10.1085/jgp.52.5.750. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Weber A. Regulatory mechanisms of the calcium transport system of fragmented rabbit sarcoplasmic rticulum. I. The effect of accumulated calcium on transport and adenosine triphosphate hydrolysis. J Gen Physiol. 1971 Jan;57(1):50–63. doi: 10.1085/jgp.57.1.50. [DOI] [PMC free article] [PubMed] [Google Scholar]

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