Book chapter
Contraction bands: differences between physiologically vs. maximally activated single heart muscle cells
Contractile Mechanisms in Muscle, Vol.170, pp.119-134
Advances in experimental medicine and biology, 37, Springer
1984
DOI: 10.1007/978-1-4684-4703-3_11
PMID: 6741691
Abstract
High resolution interference and phase microscopy were used to inspect the striations' appearance in shortening rat heart cells. Isolated cells were treated with detergent so that shortening could be graded by addition of calcium. Upon activation sarcomeres shortened to form (a) contraction densities in the middle of the A band at 1.7 micrometer (b) disappearance of the I bands and (c) phase brightening of the A bands at 1.6 micrometer and (d) dense Cz contraction bands at shorter lengths. These changes are totally consistent with the uniform sliding of myofilaments of previously accepted fixed dimensions. However, the striated patterns differed significantly in intact cells which were electrically stimulated to shorten. Here individual A bands remained distinct, without phase brightening or contraction band formation despite sarcomere shortening to less than the length of the A band as measured in the unstimulated cell. Maximal activation of intact cells by barium contracture elicited the full sequence of striation changes (a-d) seen in the chemically skinned cells. Light diffraction analysis gave comparable interpretation, i.e., the protein within the shortened sarcomere in the physiologically activated cardiac cell is more narrowly distributed than expected for thick filaments of fixed dimensions. These optical differences may reflect the restricted presence of the globular myosin heads at the ends of the cardiac sarcomere. This situation would explain the narrow range of the cardiac length-tension relation.
Details
- Title: Subtitle
- Contraction bands: differences between physiologically vs. maximally activated single heart muscle cells
- Creators
- J W KruegerB London
- Resource Type
- Book chapter
- Publication Details
- Contractile Mechanisms in Muscle, Vol.170, pp.119-134
- Publisher
- Springer; Boston, MA
- Series
- Advances in experimental medicine and biology; 37
- DOI
- 10.1007/978-1-4684-4703-3_11
- PMID
- 6741691
- ISSN
- 0065-2598
- Grant note
- HL 18824 / NHLBI NIH HHS HL 21325 / NHLBI NIH HHS
- Language
- English
- Date published
- 1984
- Academic Unit
- Molecular Physiology and Biophysics; Cardiovascular Medicine; Internal Medicine
- Record Identifier
- 9984025404502771
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