Contractile properties and myosin expression in rats  born and reared in hypergravity

Picquet, Florence; Bouët, Valentine; Canu, Marie‐Hélène; Stevens, Laurence; Mounier, Yvonne; Lacour, Michel; Falempin, Maurice

doi:10.1152/ajpregu.00643.2001

Cited by 20 publications

(37 citation statements)

References 32 publications

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“…In a recent study on rats reared in HG (Picquet et al, 2002), we showed that the slow soleus muscle studied in situ presented an increase in maximal and twitch tensions and was changed into a slower type, for both contractile parameters and MHC isoform content, while the fast plantaris was less affected. Therefore the results obtained under lifelong conditions of hypergravity, when compared to both microgravity and hypergravity applied to adults, appeared opposite in terms of generated forces and MHC isoform transitions.…”

Section: Introductionmentioning

confidence: 81%

“…For this purpose, the different objectives of this work were: (1) analysis, at the cellular level, of the Ca 2+ activation characteristics in relation to the forces developed by single fibers, in order to complete the study of Picquet et al (2002), who showed, at the whole muscle level, a reduction of the absolute twitch and maximal tetanic forces, as well as a decrease in fiber cross sectional area after HG. (2) To study more deeply phenotype acquisition in muscles continuously exposed to 2·g.…”

Section: Introductionmentioning

confidence: 99%

“…The analysis in Picquet et al (2002) was limited to the MHC, so to obtain a more complete understanding of the isoform transitions occurring after HG, we studied the three subunits of the troponin molecule (TnC, TnT and TnI, contributing to the regulation of Ca 2+ activation properties) and the set of MLC, especially the regulatory MLC2, known to modulate the Ca 2+ sensitivity of the contractile proteins by its phosphorylation state (Sweeney and Stull, 1996). Slow-to-slower MHC changes in contractile properties have already been described in CBR soleus muscle in situ (Picquet et al, 2002), so a study of MLC2 phosphorylation could contribute to our knowledge of the regulation of this phenotypical modification. Indeed, we have recently reported an increase of MLC2 phosphorylation associated with slow-to-fast transitions induced by hindlimb unloading in rat soleus muscle .…”

Section: Introductionmentioning

confidence: 99%

“…Thus, we hypothesize that the slow-to-slower characteristics acquired after HG were associated with a decrease in MLC2 phosphorylation. (3) To estimate by reverse transcriptionpolymerase chain reaction (RT-PCR) analyses, the gene regulation of the MHC slow-to-slower transition observed previously (Picquet et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Hypergravity from conception to adult stage: effects on contractile properties and skeletal muscle phenotype

Bozzo¹,

Stevens²,

Bouët

et al. 2004

Journal of Experimental Biology

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SUMMARY This study examined the effects of an elevation of the gravity factor(hypergravity – 2 g) on the molecular and functional characteristics of rat soleus and plantaris muscles. Long Evans rats were conceived, born and reared (CBR) continuously in hypergravity conditions until the age of 100 days. Whole muscle morphological parameters, Ca2+activation characteristics from single skinned fibers, troponin (Tn) subunit and myosin heavy (MHC) and light (MLC) chains isoform compositions were examined in CBR and control muscles from age-paired terrestrial rats. Decreases in body and muscle mass in soleus and plantaris muscles were observed and associated, in the soleus, with a decrease in fiber diameter. The specific force of CBR soleus fibers was increased, and correlated with the elevation of Ca2+ affinity. This was accompanied by slow-to-slower TnC and TnI isoform transitions and a rearrangement in TnT fast isoform content. The MHC transformations of the soleus after hypergravity were associated with the up (down)-regulation of the MHCI (MHCIIa) mRNA isoforms. The MLC2 phosphorylation state remained unchanged in the soleus muscle. The results suggested that the gravity factor could interact with rat muscle development and that hypergravity experiments could provide good tools for the study of myofibrillar protein plasticity and their associated pathways of regulation.

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Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hypergravity from conception to adult stage: effects on contractile properties and skeletal muscle phenotype

Bozzo¹,

Stevens²,

Bouët

et al. 2004

Journal of Experimental Biology

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“…Section 1734 solely to indicate this fact. portant role in determining how fast the fiber can be activated and relax (41).In the adult Long-Evans hooded rat, EDL and SOL muscles do not overlap in their patterns of MHC expression and fiber type composition, with the EDL muscle containing only type IIB and IID fibers and a small fraction of type IIB/D hybrid fibers (14) and SOL containing only type I and IIA fibers and a small fraction of type I/IIA hybrid fibers (14,35). In this study we used mechanically skinned muscle fiber preparations from Long-Evans hooded rats to investigate MHC isoform expression, SR properties, and contractile activation characteristics at the single fiber level.…”

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confidence: 99%

Denervation produces different single fiber phenotypes in fast- and slow-twitch hindlimb muscles of the rat

Patterson

Stephenson²,

Stephenson³

2006

American Journal of Physiology-Cell Physiology

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son. Denervation produces different single fiber phenotypes in fast-and slow-twitch hindlimb muscles of the rat. Am J Physiol Cell Physiol 291: C518 -C528, 2006. First published April 12, 2006 doi:10.1152/ajpcell.00013.2006.-Using a single, mechanically skinned fiber approach, we tested the hypothesis that denervation (0 to 50 days) of skeletal muscles that do not overlap in fiber type composition [extensor digitorum longus (EDL) and soleus (SOL) muscles of Long-Evans hooded rats] leads to development of different fiber phenotypes. Denervation (50 day) was accompanied by 1) a marked increase in the proportion of hybrid IIB/D fibers (EDL) and I/IIA fibers (SOL) from 30% to Ͼ75% in both muscles, and a corresponding decrease in the proportion of pure fibers expressing only one myosin heavy chain (MHC) isoform; 2) complex muscle-and fiber-type specific changes in sarcoplasmic reticulum Ca 2ϩ -loading level at physiological pCa ϳ7.1, with EDL fibers displaying more consistent changes than SOL fibers; 3) decrease by ϳ50% in specific force of all fiber types; 4) decrease in sensitivity to Ca 2ϩ , particularly for SOL fibers (by ϳ40%); 5) decrease in the maximum steepness of the force-pCa curves, particularly for the hybrid I/IIA SOL fibers (by ϳ35%); and 6) increased occurrence of biphasic behavior with respect to Sr 2ϩ activation in SOL fibers, indicating the presence of both slow and fast troponin C isoforms. No fiber types common to the two muscles were detected at any time points (day 7, 21, and 50) after denervation. The results provide strong evidence that not only neural factors, but also the intrinsic properties of a muscle fiber, influence the structural and functional properties of a particular muscle cell and explain important functional changes induced by denervation at both whole muscle and single cell levels. mechanically skinned fibers; myosin heavy chain isoforms; lineage; sarcoplasmic reticulum; Ca 2ϩ and Sr 2ϩ sensitivity; Long-Evans hooded rat MAMMALIAN SKELETAL MUSCLE fibers display a broad spectrum of structural and functional characteristics determined by the complement of homologous, but not identical, molecular structures involved in the excitation-contraction-relaxation cycle (33,34,41). Cross-innervation (4, 6), denervation (16,17,26,28,37), and chronic low-frequency stimulation (7,20,33,34) experiments have produced compelling evidence that the pattern of neural stimulation plays a crucial role in determining the functional and/or structural properties of skeletal muscle (38). However, neural control of fiber phenotype does not extend to the entire complement of cellular structures responsible for muscle fiber function, as demonstrated by crossinnervation studies. For example, when the extensor digitorum longus (EDL) muscle of the rat, a typically fast-twitch muscle, was cross-innervated by the nerve of the soleus (SOL) muscle, a typically slow-twitch muscle, the twitch time course of the cross-innervated muscle remained considerably faster than the twitch of the typical SOL muscle, even 16 ...

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Skeletal Muscle Plasticity in Health and Disease

Bottinelli¹,

Reggiani²

2006

Advances in Muscle Research

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Contractile properties and myosin expression in rats born and reared in hypergravity

Cited by 20 publications

References 32 publications

Hypergravity from conception to adult stage: effects on contractile properties and skeletal muscle phenotype

Hypergravity from conception to adult stage: effects on contractile properties and skeletal muscle phenotype

Denervation produces different single fiber phenotypes in fast- and slow-twitch hindlimb muscles of the rat

Skeletal Muscle Plasticity in Health and Disease

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