MHC isoform composition and Ca<sup>2+</sup>- or Sr<sup>2+</sup>-activation properties of rat skeletal muscle fibers

Bortolotto, Susan K.; Cellini, Maria.; Stephenson, D. George; Stephenson, Gabriela M. M.

doi:10.1152/ajpcell.2000.279.5.c1564

Cited by 65 publications

(95 citation statements)

References 39 publications

(50 reference statements)

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“…The initial analyses of the diaphragm muscle consisted of 278 fibers. However, this distribution was markedly different from that published by other investigators (5,32). Hence, the sampling of the diaphragm muscle was repeated, giving rise to the large no.…”

Section: Methodsmentioning

confidence: 56%

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Caiozzo¹,

Baker²,

Huang³

et al. 2003

American Journal of Physiology-Regulatory, Integrative and Comp

101

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Previous studies have reported the existence of skeletal muscle fibers that coexpress multiple myosin heavy chain isoforms. These surveys have usually been limited to studying the polymorphic profiles of skeletal muscle fibers from a limited number of muscles (i.e., usually <4). Additionally, few studies have considered the functional implications of polymorphism. Hence, the primary objective of this study was to survey a relatively large number of rat skeletal muscle/muscle regions and muscle fibers ( n≈ 5,000) to test the hypothesis that polymorphic fibers represent a larger fraction of the total pool of fibers than do so-called monomorphic fibers, which express only one myosin heavy chain isoform. Additionally, we used Hill's statistical model of the force-velocity relationship to differentiate the functional consequences of single-fiber myosin heavy chain isoform distributions found in these muscles. The results demonstrate that most muscles and regions of rodent skeletal muscles contain large proportions of polymorphic fibers, with the exception of muscles such as the slow soleus muscle and white regions of fast muscles. Several muscles were also found to have polymorphic profiles that are not consistent with the I↔IIA↔IIX↔IIB scheme of muscle plasticity. For instance, it was found that the diaphragm muscle normally contains I/IIX fibers. Functionally, the high degree of polymorphism may 1) represent a strategy for producing a spectrum of contractile properties that far exceeds that simply defined by the presence of four myosin heavy chain isoforms and 2) result in relatively small differences in function as defined by the force-velocity relationship.

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Section: Methodsmentioning

confidence: 56%

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Caiozzo¹,

Baker²,

Huang³

et al. 2003

American Journal of Physiology-Regulatory, Integrative and Comp

101

View full text Add to dashboard Cite

show abstract

“…The "hybrid" nature of diaphragm fibers has been described elsewhere (27). The force-pSr curves were biphasic in shape and described by two sigmoidal curves fitted by a composite Marquardt nonlinear regression algorithm and, thus, required a different analysis for force-pCa curves.…”

Section: Methodsmentioning

confidence: 99%

Maternal creatine supplementation from mid-pregnancy protects the newborn spiny mouse diaphragm from intrapartum hypoxia-induced damage

et al. 2010

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ABSTRACT:We hypothesized that maternal creatine supplementation from mid-pregnancy would protect the diaphragm of the newborn spiny mouse from the effects of intrapartum hypoxia. Pregnant mice were fed a control or 5% creatine-supplemented diet from mid-gestation. On the day before term, intrapartum hypoxia was induced by isolating the pregnant uterus in a saline bath for 7.5-8 min before releasing and resuscitating the fetuses. Surviving pups were placed with a cross-foster dam, and diaphragm tissue was collected at 24 h postnatal age. Hypoxia caused a significant decrease in the cross-sectional area (ϳ19%) and contractile function (26.6% decrease in maximum Ca 2ϩ -activated force) of diaphragm fibers. The mRNA levels of the muscle mass-regulating genes MuRF1 and myostatin were significantly increased (2-fold). Maternal creatine significantly attenuated hypoxia-induced fiber atrophy, contractile dysfunction, and changes in mRNA levels. This study demonstrates that creatine loading before birth significantly protects the diaphragm from hypoxiainduced damage at birth. (Pediatr Res 68: 393-398, 2010)

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“…Such diversity is based on the distinct affinity of slow and fast TnC isoform for strontium and has become a popular method for fiber type classification in full agreement with MyHC isoform identification, given the tight coupling between TnC isoforms and MyHC isoforms (87).…”

Section: Response Of Myofibrils To Calciummentioning

confidence: 99%

Fiber Types in Mammalian Skeletal Muscles

Schiaffino

Reggiani

2011

Physiological Reviews

2,165

2,465

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Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.

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MHC isoform composition and Ca²⁺- or Sr²⁺-activation properties of rat skeletal muscle fibers

Cited by 65 publications

References 39 publications

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Maternal creatine supplementation from mid-pregnancy protects the newborn spiny mouse diaphragm from intrapartum hypoxia-induced damage

Fiber Types in Mammalian Skeletal Muscles

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MHC isoform composition and Ca2+- or Sr2+-activation properties of rat skeletal muscle fibers

Cited by 65 publications

References 39 publications

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Maternal creatine supplementation from mid-pregnancy protects the newborn spiny mouse diaphragm from intrapartum hypoxia-induced damage

Fiber Types in Mammalian Skeletal Muscles

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Product

Resources

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MHC isoform composition and Ca²⁺- or Sr²⁺-activation properties of rat skeletal muscle fibers