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Effects of spaceflight on myosin heavy-chain content, fibre morphology and succinate dehydrogenase activity in rat diaphragm.
Pflugers Arch. 2004 May; 448(2):239-47.PA

Abstract

The present study examined the effect of 14 days of exposure to microgravity during the Spacelab Life Sciences-2 (SLS-2) space shuttle mission on the myosin heavy-chain (MHC) content, fibre size and type distributions and metabolic properties of rat diaphragm. Five adult male Sprague-Dawley rats were exposed to 14 days of microgravity (SF, spaceflight) and compared to five ground-based controls (C). Immunohistochemical analyses using isoform-specific anti-MHC monoclonal antibodies revealed that 14 days of SF did not alter the proportions of type-I, -IIA, -IID/X or -IIB fibres within the crural, sternal or lateral costal regions of the diaphragm; the electrophoretically quantified MHC-isoform contents also remained unchanged. In contrast, the medial gastrocnemius (MG) and tibialis anterior (TA) muscles displayed slow-to-fast fibre type transitions: within the MG the proportion of type-IID/X fibres was reduced by 59% (P<0.04) and corresponded to a 51% increase (P<0.03) in type-IIB fibres. Within the TA, the sum of type-IID/X+IIB fibres was elevated by 24% (P<0.02) at the expense of the slower type-IIA fibres, which decreased by 33% (P<0.04). Electrophoretic analyses yielded qualitatively similar patterns of transformation. SF did not induce atrophic changes within the diaphragm, MG or TA. Succinate dehydrogenase activity remained unchanged in the crural diaphragm (P>0.96) but was 34% lower (P<0.0001) in the TA. We conclude that 14 days of SF did not alter structural or metabolic factors that are known to underlie functional properties of the diaphragm. The findings of the present study show that 14 days of SF does not induce deleterious adaptive changes in the rat diaphragm that occur in hindlimb muscles.

Authors+Show Affiliations

Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, T6G 2H9, Edmonton, Alberta, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

14985980

Citation

Hansen, Gregory, et al. "Effects of Spaceflight On Myosin Heavy-chain Content, Fibre Morphology and Succinate Dehydrogenase Activity in Rat Diaphragm." Pflugers Archiv : European Journal of Physiology, vol. 448, no. 2, 2004, pp. 239-47.
Hansen G, Martinuk KJ, Bell GJ, et al. Effects of spaceflight on myosin heavy-chain content, fibre morphology and succinate dehydrogenase activity in rat diaphragm. Pflugers Arch. 2004;448(2):239-47.
Hansen, G., Martinuk, K. J., Bell, G. J., MacLean, I. M., Martin, T. P., & Putman, C. T. (2004). Effects of spaceflight on myosin heavy-chain content, fibre morphology and succinate dehydrogenase activity in rat diaphragm. Pflugers Archiv : European Journal of Physiology, 448(2), 239-47.
Hansen G, et al. Effects of Spaceflight On Myosin Heavy-chain Content, Fibre Morphology and Succinate Dehydrogenase Activity in Rat Diaphragm. Pflugers Arch. 2004;448(2):239-47. PubMed PMID: 14985980.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of spaceflight on myosin heavy-chain content, fibre morphology and succinate dehydrogenase activity in rat diaphragm. AU - Hansen,Gregory, AU - Martinuk,Karen J B, AU - Bell,Gordon J, AU - MacLean,Ian M, AU - Martin,Thomas P, AU - Putman,Charles T, Y1 - 2004/02/17/ PY - 2003/09/25/received PY - 2003/11/26/accepted PY - 2004/2/27/pubmed PY - 2004/12/16/medline PY - 2004/2/27/entrez SP - 239 EP - 47 JF - Pflugers Archiv : European journal of physiology JO - Pflugers Arch VL - 448 IS - 2 N2 - The present study examined the effect of 14 days of exposure to microgravity during the Spacelab Life Sciences-2 (SLS-2) space shuttle mission on the myosin heavy-chain (MHC) content, fibre size and type distributions and metabolic properties of rat diaphragm. Five adult male Sprague-Dawley rats were exposed to 14 days of microgravity (SF, spaceflight) and compared to five ground-based controls (C). Immunohistochemical analyses using isoform-specific anti-MHC monoclonal antibodies revealed that 14 days of SF did not alter the proportions of type-I, -IIA, -IID/X or -IIB fibres within the crural, sternal or lateral costal regions of the diaphragm; the electrophoretically quantified MHC-isoform contents also remained unchanged. In contrast, the medial gastrocnemius (MG) and tibialis anterior (TA) muscles displayed slow-to-fast fibre type transitions: within the MG the proportion of type-IID/X fibres was reduced by 59% (P<0.04) and corresponded to a 51% increase (P<0.03) in type-IIB fibres. Within the TA, the sum of type-IID/X+IIB fibres was elevated by 24% (P<0.02) at the expense of the slower type-IIA fibres, which decreased by 33% (P<0.04). Electrophoretic analyses yielded qualitatively similar patterns of transformation. SF did not induce atrophic changes within the diaphragm, MG or TA. Succinate dehydrogenase activity remained unchanged in the crural diaphragm (P>0.96) but was 34% lower (P<0.0001) in the TA. We conclude that 14 days of SF did not alter structural or metabolic factors that are known to underlie functional properties of the diaphragm. The findings of the present study show that 14 days of SF does not induce deleterious adaptive changes in the rat diaphragm that occur in hindlimb muscles. SN - 0031-6768 UR - https://www.unboundmedicine.com/medline/citation/14985980/Effects_of_spaceflight_on_myosin_heavy_chain_content_fibre_morphology_and_succinate_dehydrogenase_activity_in_rat_diaphragm_ L2 - https://dx.doi.org/10.1007/s00424-003-1230-9 DB - PRIME DP - Unbound Medicine ER -