Force‐velocity relations and myosin heavy chain isoform compositions of skinned fibres from rat skeletal muscle.

Bottinelli, Roberto; Schiaffino, Stefano; Reggiani, Carlo

doi:10.1113/jphysiol.1991.sp018617

Cited by 433 publications

(397 citation statements)

References 33 publications

(41 reference statements)

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“…However, the contractile properties were faster in males than females, particularly in rise and relaxation with tetanic stimulation. This is most likely caused by the increased proportion of MHC 2b fibers in the male ADM muscles, which is the fiber type that produces the fastest shortening velocity (16)(17)(18). This observation is consistent with previous characterizations of fiber type distributions in murine masticatory muscles (5,19), where male muscles are comprised of a greater proportion of MHC 2b fibers both in number and proportional area.…”

Section: Discussionsupporting

confidence: 81%

Sexual dimorphism of murine masticatory muscle function

Daniels

Tian

Barton

2008

Archives of Oral Biology

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Abstract(1) Objective-To determine if gender distinctions of force generating capacity existed in murine masticatory muscles.(2) Design-In order to investigate the effect of sex on force generating capacity in this muscle group, an isolated muscle preparation was developed utilizing the murine anterior deep masseter. Age-matched male and female mice were utilized to assess function, muscle fiber type and size in this muscle.(3) Results-Maximum isometric force production was not different between age-matched male and female mice. However, the rate of force generation and relaxation was slower in female masseter muscles. Assessment of fiber type distribution by immunohistochemistry revealed a threefold decrease in the proportion of myosin heavy chain 2b positive fibers in female masseters, which correlated with the differences in contraction kinetics.(4) Conclusions-These results provide evidence that masticatory muscle strength in mice is not affected by sex, but there are significant distinctions in kinetics associated with force production between males and females.

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Section: Discussionsupporting

confidence: 81%

Sexual dimorphism of murine masticatory muscle function

Daniels

Tian

Barton

2008

Archives of Oral Biology

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“…Peak power output depends, among others, on the fiber composition of the muscle under investigation. This notion is supported by data in literature about differences in power output of distinct types of skinned fibers (3,21,32). Bottinelli and coworkers (3) reported that peak power of rat skinned fibers, measured at 12°C, was substantially higher for fast-twitch glycolytic (IIB) fibers than fast-twitch oxidative (IIA) fibers.…”

Section: Discussionsupporting

confidence: 78%

Increased muscle fatigability in GLUT-4-deficient mice

Gorselink¹,

Drost

Brouwer³

et al. 2002

American Journal of Physiology-Endocrinology and Metabolism

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plays a predominant role in glucose uptake during muscle contraction. In the present study, we have investigated in mice whether disruption of the GLUT-4 gene affects isometric and shortening contractile performance of the dorsal flexor muscle complex in situ. Moreover, we have explored the hypothesis that lack of GLUT-4 enhances muscle fatigability. Isometric performance normalized to muscle mass during a single tetanic contraction did not differ between wild-type (WT) and GLUT-4-deficient [GLUT-4(Ϫ/Ϫ)] mice. Shortening contractions, however, revealed a significant 1.4-fold decrease in peak power per unit mass, most likely caused by the fiber-type transition from fast-glycolytic fibers (IIB) to fast-oxidative fibers (IIA) in GLUT-4(Ϫ/Ϫ) dorsal flexors. In addition, the resting glycogen content was significantly lower (34%) in the dorsal flexor complex of GLUT-4(Ϫ/Ϫ) mice than in WT mice. Moreover, the muscle complex of GLUT-4(Ϫ/Ϫ) mice showed enhanced susceptibility to fatigue, which may be related to the decline in the muscle carbohydrate store. The significant decrease in relative work output during the steady-state phase of the fatigue protocol suggests that energy supply via alternative routes is not capable to compensate fully for the lack of GLUT-4. skeletal muscle; electrical stimulation GLUCOSE IS A major fuel for contracting muscle fibers (6,20). This substrate is supplied to the muscle fiber from extra-and intracellular sources, i.e., blood glucose pool and intracellular glycogen (12,25). The uptake of glucose by skeletal muscle cells is facilitated by a family of membrane-associated glucose transporters (GLUTs; see Refs. 1, 6, and 16). Basal glucose uptake is mediated via the GLUT-1 isoform, whereas the bulk of glucose is primarily transported across the sarcolemma by the insulin-and contraction-regulatable glucose transporter 9,18,24,28,29). After uptake, glucose is metabolized to generate ATP or is stored as glycogen (2). During the initial phase of moderate-intensity exercise, skeletal muscle uses the intracellular glycogen store to meet its energy demand (23). It was recently shown that, during electrical stimulation, blood-borne glucose also serves as a suitable substrate during moderate-intensity exercise in mice (27). To enable detailed studies on the specific role of GLUT-4 in glucose homeostasis in general and in muscle mechanical performance in particular, mice with the GLUT-4 gene disrupted [GLUT-4(Ϫ/Ϫ)] were generated (17,36).Despite the importance of regulatable glucose transporters for muscle energy metabolism, information on the impact of GLUT-4 deficiency on muscle contractile behavior is scarce. It was recently reported that developed isometric tension during in vitro electrical stimulation of isolated extensor digitorum longus (EDL) muscle did not differ between wild-type (WT) and GLUT-4(Ϫ/Ϫ) mice (27). Extrapolation of these findings to the in vivo situation, however, should be done with caution, since the muscle fibers were studied isolated from their natural surroundings, and onl...

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“…Thus, during swimming, it is feasible that the enhanced airway resistive load due to high flow rates during inspiration and expiration (Courteix et al 1997;Kohl et al 1997) increases strength and shortening velocity of the inspiratory muscles, and thus, in PO. Since myosin heavy-chain composition is one of the determinants of shortening velocity (Linari et al 2004), a possible mechanism underlying the improvement in PO with training may be the changes in myosin heavy-chain subtypes shown in the diaphragm of experimental animals (Bottinelli et al 1991) and human vastus lateralis muscle fibers (Linari et al 2004), and/or hypertrophy of predominantly type IIa muscle fibers (Bisschop et al 1997;Rollier et al 1998). However, further research is needed to establish the role of such changes in the increase in PO due to inspiratory muscle conditioning.…”

Section: Respiratory Muscle Functionmentioning

confidence: 99%