Book chapter
The effect of lattice spacing change on cross-bridge kinetics in rabbit psoas fibers
Mechanism of Myofilament Sliding in Muscle Contraction, Vol.332, pp.581-592
Advances in experimental medicine and biology, 332, Springer
1993
DOI: 10.1007/978-1-4615-2872-2_52
PMID: 8109370
Abstract
The effect of compression on the elementary steps of the cross-bridge cycle was investigated with the sinusoidal analysis technique and ATP hydrolysis rate measurement. The lattice spacing of rabbit psoas muscle fibers was osmotically compressed with a macromolecule, dextran T-500 (0-16%). The effects of MgATP, MgADP, Pi on exponential processes (B), (C), (D), and isometric tension were studied at different dextran concentrations. The experiments were performed at the saturating Ca concentration (pCa 4.5-4.8), 200 mM ionic strength, pH 7.0, and 20 degrees C. Our results show that the fiber width decreased linearly with an increase in the dextran concentration, and the width measurement was perfectly correlated with the lattice spacing measurement using equatorial x-ray diffraction studies. We find that the nucleotide binding steps, the ATP-isomerization step, and the cross-bridge detachment step were minimally affected by the compression. Our results indicate that the rate constant of the reverse power stroke step (k-4) decreases with mild compression (0-6.3% dextran), presumably because of the stabilization of the attached cross-bridges in the AM*DP state. We also found that the rate constant of the power stroke step (k4) decreases with higher compression (> 6.3% dextran), presumably because of increased difficulty in performing the power stroke reaction. Our results further show that the association constant (K5) of phosphate to cross-bridges is not changed with compression. The ATP hydrolysis rate declined almost linearly with an increase in the dextran concentration. This observation indicates that the rate limiting step is also affected by the lattice spacing change so that the associated rate constant (k6) becomes progressively less with compression.
Details
- Title: Subtitle
- The effect of lattice spacing change on cross-bridge kinetics in rabbit psoas fibers
- Creators
- Y Zhao - Department of Anatomy, University of Iowa, Iowa City 52242M KawaiJ Wray
- Resource Type
- Book chapter
- Publication Details
- Mechanism of Myofilament Sliding in Muscle Contraction, Vol.332, pp.581-592
- Publisher
- Springer; Boston, MA
- Series
- Advances in experimental medicine and biology; 332
- DOI
- 10.1007/978-1-4615-2872-2_52
- PMID
- 8109370
- ISSN
- 0065-2598
- Grant note
- AR21530 / NIAMS NIH HHS
- Language
- English
- Date published
- 1993
- Academic Unit
- Anatomy and Cell Biology; Internal Medicine
- Record Identifier
- 9984025558302771
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