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Effect of Active Lengthening and Shortening on Small-Angle X-ray Reflections in Skinned Skeletal Muscle Fibres. Int J Mol Sci 2021; 22:ijms22168526. [PMID: 34445232 PMCID: PMC8395229 DOI: 10.3390/ijms22168526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 01/04/2023] Open
Abstract
Our purpose was to use small-angle X-ray diffraction to investigate the structural changes within sarcomeres at steady-state isometric contraction following active lengthening and shortening, compared to purely isometric contractions performed at the same final lengths. We examined force, stiffness, and the 1,0 and 1,1 equatorial and M3 and M6 meridional reflections in skinned rabbit psoas bundles, at steady-state isometric contraction following active lengthening to a sarcomere length of 3.0 µm (15.4% initial bundle length at 7.7% bundle length/s), and active shortening to a sarcomere length of 2.6 µm (15.4% bundle length at 7.7% bundle length/s), and during purely isometric reference contractions at the corresponding sarcomere lengths. Compared to the reference contraction, the isometric contraction after active lengthening was associated with an increase in force (i.e., residual force enhancement) and M3 spacing, no change in stiffness and the intensity ratio I1,1/I1,0, and decreased lattice spacing and M3 intensity. Compared to the reference contraction, the isometric contraction after active shortening resulted in decreased force, stiffness, I1,1/I1,0, M3 and M6 spacings, and M3 intensity. This suggests that residual force enhancement is achieved without an increase in the proportion of attached cross-bridges, and that force depression is accompanied by a decrease in the proportion of attached cross-bridges. Furthermore, the steady-state isometric contraction following active lengthening and shortening is accompanied by an increase in cross-bridge dispersion and/or a change in the cross-bridge conformation compared to the reference contractions.
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Zhu J, Sabharwal T, Kalyanasundaram A, Guo L, Wang G. Topographic mapping and compression elasticity analysis of skinned cardiac muscle fibers in vitro with atomic force microscopy and nanoindentation. J Biomech 2009; 42:2143-50. [PMID: 19640539 PMCID: PMC2808505 DOI: 10.1016/j.jbiomech.2009.05.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 05/08/2009] [Accepted: 05/23/2009] [Indexed: 10/20/2022]
Abstract
Surface topography and compression elasticity of bovine cardiac muscle fibers in rigor and relaxing state have been studied with atomic force microscopy. Characteristic sarcomere patterns running along the longitudinal axis of the fibers were clearly observed, and Z-lines, M-lines, I-bands, and A-bands can be distinguished through comparing with TEM images and force curves. AFM height images of fibers had shown a sarcomere length of 1.22+/-0.02 microm (n=5) in rigor with a significant 9% increase in sarcomere length in relaxing state (1.33+/-0.03 microm, n=5), indicating that overlap moves with the changing physiological conditions. Compression elasticity curves along with sarcomere locations have been taken by AFM compression processing. Coefficient of Z-line, I-band, Overlap, and M-line are 25+/-2, 8+/-1, 10+/-1, and 17+/-1.5 pN/nm respectively in rigor state, and 18+/-2.5, 4+/-0.5, 6+/-1, and 11+/-0.5 pN/nm respectively in relaxing state. Young's Modulus in Z-line, I-band, Overlap, and M-line are 115+/-12, 48+/-9, 52+/-8, and 90+/-12 kPa respectively in rigor, and 98+/-10, 23+/-4, 42+/-4, and 65+/-7 kPa respectively in relaxing state. The elasticity curves have shown a similar appearance to the section analysis profile of AFM height images of sarcomere and the distance between adjacent largest coefficient and Young's Modulus is equal to the sarcomere length measured from the AFM height images using section analysis, indicating that mechanic properties of fibers have a similar periodicity to the topography of fibers.
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Affiliation(s)
- Jie Zhu
- Cardiac Biophysics and Bioengineering Laboratory, College of Science, Northwest A&F University, Yangling, Shaanxi 712100, China
- Biophysics Collaborative Access Team, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439-4860, United States
- Pritzker Institute of Biomedical Science & Engineering, Illinois Institute of Technology, Chicago, IL 60616-3793, United States
| | - Tanya Sabharwal
- Pritzker Institute of Biomedical Science & Engineering, Illinois Institute of Technology, Chicago, IL 60616-3793, United States
- Section of Molecular Cell and Developmental Biology, School of Biological Sciences, University of Texas, Austin, TX 78712, United States
| | - Aruna Kalyanasundaram
- Pritzker Institute of Biomedical Science & Engineering, Illinois Institute of Technology, Chicago, IL 60616-3793, United States
| | - Lianhong Guo
- Laboratory of Biomathematics, Department of Applied Mathematics, Northwest A&F University, Yangling, Shaanxi 712100, China
- Department of Applied Mathematics, College of Science and Letters, Illinois Institute of Technology, Chicago, IL 60616, United States
| | - Guodong Wang
- Cardiac Biophysics and Bioengineering Laboratory, College of Science, Northwest A&F University, Yangling, Shaanxi 712100, China
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Kuller A, Fleri W, Bluhm WF, Smith JL, Westbrook J, Bourne PE. A biologist's guide to synchrotron facilities: the BioSync web resource. Trends Biochem Sci 2002; 27:213-5. [PMID: 11943550 DOI: 10.1016/s0968-0004(02)02056-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Research at synchrotron radiation facilities, once the domain of high energy physics, now has a major impact on fields as diverse as immunology, neurobiology, physiology, molecular biology, medicine and biotechnology. This article describes the development of a comprehensive synchrotron portal and informational website (http://www.biosync.sdsc.edu) for biologists engaged in research at synchrotrons. The site automatically provides timely and accurate information in a unified format by gathering technical descriptions of synchrotron beamlines using modern information management practices.
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Affiliation(s)
- Anne Kuller
- San Diego Supercomputer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0505, USA
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