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


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 


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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

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