| Autor: |
Watanabe D; Department of Physiology Anatomy & Microbiology, La Trobe University, Melbourne, Australia. dwatanabe@hiroshima-u.ac.jp.; Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan. dwatanabe@hiroshima-u.ac.jp., Dutka TL; Department of Physiology Anatomy & Microbiology, La Trobe University, Melbourne, Australia., Lamboley CR; Department of Physiology Anatomy & Microbiology, La Trobe University, Melbourne, Australia.; School of Biomedical Sciences, The University of Queensland, Brisbane, Australia., Lamb GD; Department of Physiology Anatomy & Microbiology, La Trobe University, Melbourne, Australia. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of muscle research and cell motility [J Muscle Res Cell Motil] 2019 Dec; Vol. 40 (3-4), pp. 343-351. Date of Electronic Publication: 2019 Jun 07. |
| DOI: |
10.1007/s10974-019-09521-1 |
| Abstrakt: |
This study investigated the effects of fibre swelling on force production in rat and human skinned muscle fibres, using osmotic compression to reverse the fibre swelling. In mechanically-skinned fibres, the sarcolemma is removed but normal excitation-contraction coupling remains functional. Force responses in mechanically-skinned fibres were examined with and without osmotic compression by polyvinylpyrrolidone 40 kDa (PVP-40) or Dextran 500 kDa (dextran). Fibre diameter increased to 116 ± 2% (mean ± SEM) when rat skinned type II fibres were immersed in the standard intracellular solution, but remained close to the in situ size when 3% (mass/volume) PVP-40 or 4% Dextran were present. Myofibrillar Ca 2+ sensitivity, as indicated by pCa 50 (- log 10 [Ca 2+ ] at half-maximal force), was increased in 4% Dextran (0.072 ± 0.007 pCa 50 shift), but was not significantly changed in 3% PVP-40. Maximum Ca 2+ -activated force increased slightly to 103 ± 1% and 104 ± 1% in PVP-40 and Dextran, respectively. Both tetanic and depolarization-induced force responses in rat skinned type II fibres, elicited by electrical stimulation and ion substitution respectively, were increased by ~ 10 to 15% when the fibres were returned to their normal in situ diameter by addition of PVP-40 or Dextran. Interestingly, the potentiation of these force responses in PVP-40 was appreciably greater than could be explained by potentiation of myofibrillar function alone. These results indicate that muscle fibre swelling, as can occur with intense exercise, decreases evoked force responses by reducing both the Ca 2+ -sensitivity of the contractile apparatus properties and Ca 2+ release from the sarcoplasmic reticulum. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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