Pflügers Archiv

, Volume 391, Issue 4, pp 334–337 | Cite as

Influence of osmotic compression on calcium activation and tension in skinned muscle fibers of the rabbit

  • Robert E. Godt
  • David W. Maughan
Heart, Circulation, Respiration and Blood; Environmental and Exercise Physiology

Abstract

Single skinned muscle fibers were osmotically compressed back to and below their in situ size by addition of a large, random-coil polymer (Deytran T500;\(\bar M_{\text{N}}\)= 180,000;\(\bar M_{\text{W}}\) = 461,000) to the bathing medium. Maximal Ca2+-activated tension in fibers swollen (zero Dextran, fiber width 21% above in situ) or near in situ size (5% Dextran, in g/100 ml final solution) was similar, but compression to 86% of in situ width with 10% Dextran decreased maximal force by 15% relative to polymer-free control. While the relative tension-pCa relation in 0 and 10% Dextran was similar, with a pCa of 6.37 required for 50% activation, that in 5% Dextran was more sensitive to Ca2+, with a pCa50 of 6.66. We feel these effects are most likely due to changes in interfilament spacing with compression and that alterations in Ca2+-sensitivity might be explained by changes in cross-bridge angle or in the concomitant attachment-detachment rate constants which would be expected to influence the troponin-Ca2+ binding equilibrium, as has been proposed by others.

Key words

Cross-bridges Interfilament spacing Dextran Polymer Contraction 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Adelstein RS, Eisenberg E (1980) Regulation and kinetics of the actinmyosin-ATP interaction. Ann Rev Biochem 49:921–956Google Scholar
  2. April EW (1981) Osmotic contributions to the stability of the A-band liquid-crystal. Biophys J 33:27aGoogle Scholar
  3. April EW, Farrell M, Schreder J (1977) Osmotically-induced changes in the filament lattice of skinned striated muscle fibers. Biophys J 17:174aGoogle Scholar
  4. Best PW, Donaldson SKB, Kerrick WGL (1977) Tension in mechanically disrupted mammalian cardiac cells: effects of magnesium adenosine triphosphate. J Physiol (Lond) 265:1–17Google Scholar
  5. Brandt PW, Reuben JP, Grundfest H (1972) Regulation of tension in the skinned crayfish muscle fiber. II. Role of calcium. J Gen Physiol 59:305–317Google Scholar
  6. Bremel RD, Weber A (1972) Cooperation within actin filament in vertebrate skeletal muscle. Nature 238:97–101Google Scholar
  7. Eisenberg E, Greene LE (1980) The relation of muscle biochemistry to muscle physiology. Ann Rev Physiol 42:293–309Google Scholar
  8. Eisenberg E, Hill TL, Chen Y-D (1980) Crossbridge model of muscle contraction. Quantitative analysis. Biophys J 29:195–227Google Scholar
  9. Endo M, Kitazawa T, Iino M, Kakuta Y (1979) Effect of “viscosity” of the medium on mechanical properties of skinned skeletal muscle fibers. In: Sugi H, Pollack GH (eds) Cross-bridge mechanism in muscle contraction. University Park Press, Baltimore, pp 365–376Google Scholar
  10. Fabiato A, Fabiato F (1978) Myofilament-generated tension oscillations during partial calcium activation and activation dependence of the sarcomere length-tension relation of skinned cardiac cells. J Gen Physiol 72:667–699Google Scholar
  11. Fuchs F (1978) On the relation between filament overlap and the number of calcium-binding sites in glycerinated muscle fibers. Biophys J 21:273–277Google Scholar
  12. Godt RE (1974) Calcium-activated tension of skinned muscle fibers of the frog. Dependence on magnesium adenosine triphosphate concentration. J Gen Physiol 63:722–739Google Scholar
  13. Godt RE, Maughan DW (1977) Swelling of skinned muscle fibers of the frog. Experimental observations. Biophys J 19:103–116Google Scholar
  14. Godt RE, Morgan JL (1981) Effect of osmotic compression on calcium activation and force production of skinned rabbit muscle fibers. Biophys J 33:30aGoogle Scholar
  15. Goldman YE, Matsubara I, Simmons RM (1979) Lateral filamentary spacing in frog skinned muscle fibers in the relaxed and rigor states. J Physiol (Lond) 295:81pGoogle Scholar
  16. Krasner B, Maughan DW (1981) Dextran T500 decreases skinned fiber width, tension, and ATPase. Biophys J 33:27aGoogle Scholar
  17. Magid A, Reedy MK (1980) X-ray diffraction observations of chemically skinned frog skeletal muscle processed by an improved method. Biophys J 30:27–40Google Scholar
  18. Maughan DW, Godt RE (1979) Stretch and radial compression studies on relaxed skinned muscle fibers of the frog. Biophys J 28:391–402Google Scholar
  19. Maughan DW, Godt RE (1981a) Radial forces within muscle fibers in rigor. J Gen Physiol 77:49–64Google Scholar
  20. Maughan DW, Godt RE (1981b) Inhibition of force production in compressed skinned muscle fibers of the frog. Pflügers Arch 390:161–163Google Scholar
  21. Murray JM, Weber A (1980) Cooperativity of the calcium switch of regulated rabbit actomyosin system. Mol Cell Biochem 35:11–15Google Scholar
  22. Robinson RA, Stokes RH (1965)Electrolyte solutions, second edition revised. Butterworths, London, pp 311–312Google Scholar
  23. Schoenberg M (1980a) Geometrical factors influencing muscle force development. I. The effect of filament spacing upon axial forces. Biophys J 30:51–68Google Scholar
  24. Schoenberg M (1980b) Geometrical factors influencing muscle force development. II. Radial forces. Biophys J 30:69–78Google Scholar
  25. Stephenson EW (1981) Activation of fast skeletal muscles: contributions of studies on skinned fibers. Am J Physiol 240:C1-C19Google Scholar
  26. Weber A, Murray JM (1973) Molecular control mechanisms in muscle contraction. Physiol Rev 53:612–673Google Scholar

Copyright information

© Springer-Verlag 1981

Authors and Affiliations

  • Robert E. Godt
    • 1
  • David W. Maughan
    • 2
  1. 1.Department of PhysiologyMedical College of GeorgiaAugustaUSA
  2. 2.Department of Physiology and BiophysicsUniversity of Vermont College of MedicineBurlingtonUSA

Personalised recommendations