Journal article
Biomechanical evaluation of flash-frozen and cryo-sectioned papillary muscle samples by using sinusoidal analysis: cross-bridge kinetics and the effect of partial Ca 2+ activation
Journal of muscle research and cell motility, Vol.45(3), pp.95-113
04/16/2024
DOI: 10.1007/s10974-024-09667-7
PMID: 38625452
Abstract
We examined the integrity of flash-frozen and cryo-sectioned cardiac muscle preparations (introduced by Feng and Jin, 2020) by assessing tension transients in response to sinusoidal length changes at varying frequencies (1-100 Hz) at 25 °C. Using 70-μm-thick sections, we isolated fiber preparations to study cross-bridge (CB) kinetics: preparations were activated by saturating Ca
as well as varying concentrations of ATP and phosphate (Pi). Our results showed that, compared to ordinary skinned fibers, in-series stiffness decreased to 1/2, which resulted in a decrease of isometric tension to 62%, but CB kinetics and Ca
sensitivity were little affected. The pCa study demonstrated that the rate constant of the force generation step (2πb) is proportionate to [Ca
] at < 5 μM, suggesting that the activation mechanism can be described by a simple second order reaction. We also found that tension, stiffness, and magnitude parameters are related to [Ca
] by the Hill equation, with a cooperativity coefficient of 4-5, which is consistent with the fact that Ca
activation mechanisms involve cooperative multimolecular interactions. Our results support the long-held hypothesis that Process C (Phase 2) represents the CB detachment step, and Process B (Phase 3) represents the force generation step. Moreover, we discovered that constant H may represent the work-performing step in cardiac preparations. Our experiments demonstrate excellent CB kinetics with two well-defined exponentials that can be more distinguished than those found using ordinary skinned fibers. Flash-frozen and cryo-sectioned preparations are especially suitable for multi-institutional collaborations nationally and internationally because of their ease of transportation.
Details
- Title: Subtitle
- Biomechanical evaluation of flash-frozen and cryo-sectioned papillary muscle samples by using sinusoidal analysis: cross-bridge kinetics and the effect of partial Ca 2+ activation
- Creators
- Jing Xi - University of IowaHan-Zhong Feng - University of Illinois ChicagoJian-Ping Jin - University of Illinois ChicagoJinxiang Yuan - Jining Medical UniversityMasataka Kawai - Department of Anatomy and Cell Biology, College of Medicine, University of Iowa, Iowa City, IA, 52242, USA. masataka-kawai@uiowa.edu
- Resource Type
- Journal article
- Publication Details
- Journal of muscle research and cell motility, Vol.45(3), pp.95-113
- DOI
- 10.1007/s10974-024-09667-7
- PMID
- 38625452
- NLM abbreviation
- J Muscle Res Cell Motil
- ISSN
- 0142-4319
- eISSN
- 1573-2657
- Publisher
- Springer
- Grant note
- HL127691 / Office of Extramural Research, National Institutes of Health HL138007 / National Institute for Health Care Management Foundation 600791001 / Research Start-up Fund of Jining Medical University
- Language
- English
- Electronic publication date
- 04/16/2024
- Academic Unit
- Anatomy and Cell Biology; Internal Medicine
- Record Identifier
- 9984616957902771
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