A single-fibre study of the relationship between MHC and TnC isoform composition in rat skeletal muscle

O'Connell, Brett; Nguyễn, Long Thanh; Stephenson, Gabriela M. M.

doi:10.1042/bj20031170

Cited by 25 publications

(47 citation statements)

References 28 publications

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“…These fibres were denoted as mixed according to the classification of Bortolotto et al 5 and most probably contained both fast and slow isoforms of TnC and both type I and type II MHC. 5,15 In apparent accord with this, it can be seen in Table 1 …”

Section: Properties Of the Contractile Apparatussupporting

confidence: 83%

“…5 The Sr 2+ -activation characteristics of a fibre are determined by the type of TnC present (TnC-fast or TnCslow), but this, in fact, is always very closely related to MHC isoform composition of the fibre in non-transforming skeletal muscles of adult rat. 15 In a study of 241 single fibres from rat muscle, it was found that every fibre displaying simple Sr 2+ -activation characteristics was composed of at least 80%, and in most cases 100%, of one or other of the two broad classes of MHC, slow (type I) or fast (types IIA, IIX and IIB). Fibres in which the difference between the pCa 50 Fig.…”

Section: The Sr 2+ -And Ca 2+ -Activation Characteristics and Mhc Isomentioning

confidence: 98%

“…The increase in Sr 2+ sensitivity was much greater than the increase in Ca 2+ sensitivity, with the difference between the pCa 50 and the pSr 50 being only 0.33 ± 0.01 (Table 1). These fibres were all defined as ST with regard to their contractile properties and almost certainly contained mostly slow-twitch TnC and type I MHC 5,15 (see Discussion).…”

Section: Properties Of the Contractile Apparatusmentioning

confidence: 99%

“…It has been shown recently that the Ca 2+ -and Sr 2+ -activation characteristics of a skinned fibre 13,14 are absolutely indicative of the troponin C (TnC) isoform(s) present (TnC-fast and TnC-slow), which, in turn, is highly indicative of the MHC isoform(s) present. 5,15 In addition, Fryer and Stephenson 16 used a fibre-lysing technique to assay the maximum Ca 2+ -holding capacity of the SR in rat fibres and found that fibres from the EDL muscle (probably containing almost exclusively MHC type II) had a maximum SR capacity approximately threefold larger than slow-twitch fibres from the soleus muscle (i.e. those containing predominantly MHC type I, as indicated by their Sr 2+ -activation characteristics).…”

Section: Introductionmentioning

confidence: 98%

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Matching of Sarcoplasmic Reticulum and Contractile Properties in Rat Fast‐ and Slow‐twitch Muscle Fibres

Trinh

Lamb

2006

Clin Exp Pharma Physio

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1. The twitch characteristics (fast-twitch or slow-twitch) of skeletal muscle fibres are determined not only by the contractile apparatus properties of the fibre, but also by the time-course of Ca2+ release and re-uptake by the sarcoplasmic reticulum (SR). The present study examined, in individual fibres from non-transforming muscle of the rat, whether particular SR properties are matched to the contractile apparatus properties of the fibre, in particular in the case of fibres with fast-twitch contractile apparatus located in a slow-twitch muscle, namely the soleus. 2. Force was recorded in single, mechanically skinned fibres from extensor digitorum longus (EDL), gastrocnemius, peroneus longus and soleus muscles. Using repeated cycles in which the SR was emptied of all releasable Ca2+ and then reloaded, it was possible to determine the relative amount of Ca2+ present in the SR endogenously, the maximum SR capacity and the rate of Ca2+ loading. The sensitivity of the contractile apparatus to Ca2+ and Sr2+ was used to classify the fibres as fast-twitch (FT), slow-twitch (ST) or mixed (< 3% of the fibres examined) and thereby identify the likely troponin C and myosin heavy chain types present. 3. There was no significant difference in SR properties between the groups of FT fibres obtained from the four different muscles, including soleus. Despite some overlap in the SR properties of individual fibres between the FT and ST groups, the properties of the FT fibres in all four muscles studied were significantly different from those of the ST and mixed fibres. 4. In general, in FT fibres the SR had a larger capacity and the endogenous Ca2+ content was a relatively lower percentage of maximum compared with ST fibres. Importantly, in terms of their SR properties, FT fibres from soleus muscle more closely resembled FT fibres from other muscles than they did ST fibres from soleus muscle.

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Section: Properties Of the Contractile Apparatussupporting

confidence: 83%

Section: The Sr 2+ -And Ca 2+ -Activation Characteristics and Mhc Isomentioning

confidence: 98%

Section: Properties Of the Contractile Apparatusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Matching of Sarcoplasmic Reticulum and Contractile Properties in Rat Fast‐ and Slow‐twitch Muscle Fibres

Trinh

Lamb

2006

Clin Exp Pharma Physio

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“…SDS-PAGE was performed on 7.5% resolving gels according to the method of O'Connell et al (21); the samples were thawed and vortexed thoroughly before being boiled for 5 min, and each well was loaded with 5 l of sample and 5 l of sample buffer. MHC markers consisting of single rabbit psoas and soleus fibers (muscles containing almost pure IIX and I isoforms, respectively) were then loaded in the end and middle lanes.…”

Section: Methodsmentioning

confidence: 99%

Passive properties of the diaphragm in COPD

Moore

Stubbings²,

Swallow³

et al. 2006

Journal of Applied Physiology

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tural adaptations that occur in the diaphragm muscle of patients with chronic obstructive pulmonary disease (COPD), namely an increase in type I fibers and a decrease in type II fibers, have been explored in terms of the active contractile properties of the diaphragm. The aim of this study was to test the passive properties of the diaphragm by measuring the force response of relaxed diaphragm muscle fibers to stretching to determine the effect of COPD on these properties. Costal diaphragm biopsies were taken from patients with COPD and from controls with normal pulmonary function. From these biopsies, titin expression was assessed in diaphragm homogenates by gel electrophoresis, and the restoring force was measured by incremental stretching of single fibers in the relaxed state and measuring the force response to stretching. A quadratic model was used to illustrate the relationship between restoring force and muscle fiber length, and it revealed that COPD fibers generate significantly lower restoring forces than control fibers as judged by the area under the force-length curve. Furthermore, this finding applies to both type I and type II fibers. Gel electrophoresis revealed different titin isoforms in COPD and controls, consistent with the conclusion that COPD results not only in a change in muscle fiber-type distribution but in a structural change in the titin molecule in all muscle fiber types within the diaphragm. This may assist the muscle with the energetic changes in the length of the diaphragm required during breathing in COPD.titin; passive tension; chronic obstructive pulmonary disease CHRONIC OBSTRUCTIVE PULMONARY disease (COPD) is one of the leading causes of death and disability in the developed world (17,20) and is characterized by progressive airflow limitation, which is largely irreversible (20). Because of the increased resistance to airflow, pulmonary hyperinflation can develop (18), the consequence of which is a flattening of the diaphragm resulting in a loss of its natural, curved, anatomic shape. This decreases the zone of apposition of the diaphragm to the chest wall (2, 13), which is essential for development of transdiaphragmatic pressure, and so the capacity of the diaphragm to generate negative intrathoracic pressures decreases in pulmonary hyperinflation (13,27).It is has been documented that in COPD the diaphragm undergoes an adaptation to compensate for the mechanical stresses that pulmonary hyperinflation places on it. These changes involve an alteration in the myosin heavy chain (MHC) isoform expression (14), with an increase in the proportion of type I fibers, and there is evidence of structural change also occurring within the diaphragm fibers at a subcellular level. Studies have shown that in chronic hyperinflation the resting sarcomere length in human diaphragm muscle fibers decreases (23). In emphysematous rodent models, it has been proposed that the total number of sarcomeres available in the shortened muscle fiber may be fewer than in normal controls, due to a loss in their n...

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How Animals Move: Comparative Lessons on Animal Locomotion

Schaeffer

Lindstedt

2013

Comprehensive Physiology

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Comparative physiology often provides unique insights in animal structure and function. It is specifically through this lens that we discuss the fundamental properties of skeletal muscle and animal locomotion, incorporating variation in body size and evolved difference among species. For example, muscle frequencies in vivo are highly constrained by body size, which apparently tunes muscle use to maximize recovery of elastic recoil potential energy. Secondary to this constraint, there is an expected linking of skeletal muscle structural and functional properties. Muscle is relatively simple structurally, but by changing proportions of the few muscle components, a diverse range of functional outputs is possible. Thus, there is a consistent and predictable relation between muscle function and myocyte composition that illuminates animal locomotion. When animals move, the mechanical properties of muscle diverge from the static textbook force-velocity relations described by A. V. Hill, as recovery of elastic potential energy together with force and power enhancement with activation during stretch combine to modulate performance. These relations are best understood through the tool of work loops. Also, when animals move, locomotion is often conveniently categorized energetically. Burst locomotion is typified by high-power outputs and short durations while sustained, cyclic, locomotion engages a smaller fraction of the muscle tissue, yielding lower force and power. However, closer examination reveals that rather than a dichotomy, energetics of locomotion is a continuum. There is a remarkably predictable relationship between duration of activity and peak sustainable performance.

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A single-fibre study of the relationship between MHC and TnC isoform composition in rat skeletal muscle

Cited by 25 publications

References 28 publications

Matching of Sarcoplasmic Reticulum and Contractile Properties in Rat Fast‐ and Slow‐twitch Muscle Fibres

Matching of Sarcoplasmic Reticulum and Contractile Properties in Rat Fast‐ and Slow‐twitch Muscle Fibres

Passive properties of the diaphragm in COPD

How Animals Move: Comparative Lessons on Animal Locomotion

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