DOI: 10.5061/dryad.jf35g
title: Data from: Thixotropy and rheopexy of muscle fibers probed using sinusoidal oscillations

description: Length changes of muscle fibers have previously been shown to result in a
 temporary reduction in fiber stiffness that is referred to as thixotropy.
 Understanding the mechanism of this thixotropy is important to our
 understanding of muscle function since there are many instances in which
 muscle is subjected to repeated patterns of lengthening and shortening. By
 applying sinusoidal length changes to one end of single permeabilized
 muscle fibers and measuring the force response at the opposite end, we
 studied the history-dependent stiffness of both relaxed and activated
 muscle fibers. For length change oscillations greater than 1 Hz, we
 observed thixotropic behavior of activated fibers. Treatment of these
 fibers with EDTA and blebbistatin, which inhibits myosin-actin
 interactions, quashed this effect, suggesting that the mechanism of muscle
 fiber thixotropy is cross-bridge dependent. We modeled a half-sarcomere
 experiencing sinusoidal length changes, and our simulations suggest that
 thixotropy could arise from force-dependent cross-bridge kinetics.
 Surprisingly, we also observed that, for length change oscillations less
 than 1 Hz, the muscle fiber exhibited rheopexy. In other words, the
 stiffness of the fiber increased in response to the length changes.
 Blebbistatin and EDTA did not disrupt the rheopectic behavior, suggesting
 that a non-cross-bridge mechanism contributes to this phenomenon.
description: Relaxed Fiber Before
 Treatment 1This is data from the
 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle
 fiber experiencing sinusoidal oscillationsDA_052212_f3_A.datRelaxed Fiber Before Treatment 2This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillationsDA_052212_f4_A.datRelaxed Fiber Before Treatment 3This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillationsDA_052312_f1_A.datRelaxed Fiber Before Treatment 4This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillationsDA_052412_f1_A.datRelaxed Fiber Before Treatment 5This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillationsDA_052412_f3_A.datRelaxed Fiber Before Treatment 6This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillationsDA_052512_f1_A.datActivated Fiber Before Treatment 1This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052212_f2_A.datActivated Fiber Before Treatment 2This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052212_f3_B.datActivated Fiber Before Treatment 3This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052212_f4_B.datActivated Fiber Before Treatment 4This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052312_f1_B.datActivated Fiber Before Treatment 5This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052412_f1_B.datActivated Fiber Before Treatment 6This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052412_f3_B.datActivated Fiber Before Treatment 7This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052512_f2_A.datActivated Fiber Before Treatment 8This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillationsDA_052512_f4_A.datActivated Fiber After Treatment 1This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillations following treatment with blebbistatin and EDTADA_052512_f4_G.datActivated Fiber After Treatment 2This is data from the 600A Digital Controller (Aurora Scientific Inc.) for an activated muscle fiber experiencing sinusoidal oscillations following treatment with blebbistatin and EDTADA_052312_f1_H.datRelaxed Fiber After Treatment 1This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillations following treatment with blebbistatin and EDTADA_052512_f4_H.datRelaxed Fiber After Treatment 2This is data from the 600A Digital Controller (Aurora Scientific Inc.) for a relaxed muscle fiber experiencing sinusoidal oscillations following treatment with blebbistatin and EDTADA_052312_f1_I.dat