Carbon-13 and proton magnetic resonance of mouse muscle

Fung, B. M.

doi:10.1016/s0006-3495(77)85591-4

Cited by 24 publications

(8 citation statements)

References 21 publications

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“…Also, the magnitude (11-15% MT, r) and T 2 value (Ͼ100 ms) of component D closely resemble those of the component attributed to extracellular fluid (4,15,20). Critics of the water compartment model have suggested that the ex vivo T 2 component attributed to extracellular fluid was a postmortum artifact (17), but the present observation of a similar component in vivo contradicts that argument. The relative volumes of the both the extra (M D )-and intracellular fluid (M B ϩ M C ) in resting muscle were in close agreement with values determined with radio tracers (8,26,36,40).…”

Section: Discussionsupporting

confidence: 62%

Effects of exercise on muscle transverse relaxation determined by MR imaging and in vivo relaxometry

Saab

Thompson

Marsh

2000

Journal of Applied Physiology

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The purpose of this study was to determine the effects of intense exercise on the proton transverse (T(2)) relaxation of human skeletal muscle. The flexor digitorium profundus muscles of 12 male subjects were studied by using magnetic resonance imaging (MRI; 6 echoes, 18-ms echo time) and in vivo magnetic resonance relaxometry (1,000 echoes, 1.2-ms echo time), before and after an intense handgrip exercise. MRI of resting muscle produced a single T(2) value of 32 ms that increased by 19% (P < 0.05) with exercise. In vivo relaxometry showed at least three T(2) components (>5 ms) for all subjects with mean values of 21, 40, and 137 ms and respective magnitudes of 34, 49, and 14% of the total magnetic resonance signal. These component magnitudes changed with exercise by -44% (P < 0.05), +52% (P < 0.05), and +23% (P < 0.05), respectively. These results demonstrate that intense exercise has a profound effect on the multicomponent T(2) relaxation of muscle. Changes in the magnitudes of all the T(2) components synergistically increase MRI T(2), but changes in the two shortest T(2) components predominate.

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Section: Discussionsupporting

confidence: 62%

Effects of exercise on muscle transverse relaxation determined by MR imaging and in vivo relaxometry

Saab

Thompson

Marsh

2000

Journal of Applied Physiology

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“…Foster et al (7) suggested that its source was relatively mobile protons in tissue protein and lipid. We compared the 13C and 'H spectra of skeletal muscje (8), and supported their suggestions. Recently, Peemoeller and Pintar (9) and Peemoeller et al (10) proposed that the fraction with a decay constant of -5 ms is due to protons in large molecules (,30%) plus protons in water (-70%).…”

Section: Discussionsupporting

confidence: 62%

Nuclear magnetic resonance transverse relaxation in muscle water

Fung¹,

Puon²

1981

Biophysical Journal

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The origin of the nonexponentiality of proton spin echoes of skeletal muscle has been carefully examined. It is shown that the slowly decaying part of the proton spin echoes is not due to extracellular water. First, for muscle from mice with in vivo deuteration, the deuteron spin echoes were also nonexponential, but the slowly decaying part had a larger weighing factor. Second, for glycerinated muscle in which cell membranes were disrupted, the proton spin echoes were similar to those in intact muscle. Third, the nonexponentiality of the proton spin echoes in intact muscle increased when postmortem rigor set in. Finally, when the lifetimes of extracellular water and intracellular water were taken into account in the exchange, it was found that the two types of water would not give two resolvable exponentials with the observed decay constants. It is suggested that the unusually short T2's and the nonexponential character of the spin echoes of proton and deuteron in muscle water are mainly due to hydrogen exchange between water and functional groups in the protein filaments. These groups have large dipolar or quadrupolar splittings, and undergo hydrogen exchange with water at intermediate rates. The exchange processes and their effects on the spin echoes are pH-dependent. The dependence of transverse relaxation of pH was observed in glycerinated rabbit psoas muscle fibers.

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“…The smaller slowly exchanging bound water fraction may determine much of the MR relaxation character of muscle cells. Muscle cell contraction involves conformational changes in the large contractile proteins as well as mechanical alterations in intracellular surfaces (11). Such surface alterations may affect the bound water layer, which in turn may determine MR relaxation (10).…”

Section: Rmmentioning

confidence: 99%

Magnetic resonance imaging and electromyography as indexes of muscle function

Adams

Duvoisin

Dudley

1992

Journal of Applied Physiology

219

213

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1992.-Electromyography (EMG) is commonly used to determine the electrical activity of skeletal muscle during contraction. To date, independent verification of the relationship between muscle use and EMG has not been provided. It has recently been shown that relaxation-(e.g., T 2 ) weighted magnetic resonance images (MRI) of skeletal muscle demonstrate exercise-induced contrast enhancement that is graded with exercise intensity. This study was conducted to test the hypothesis that exercise-induced magnetic resonance (MR) contrast shifts would relate to EMG amplitude if both measures reflect muscle use during exercise. Both MRI and EMG data were collected for separate eccentric (ECC) and concentric (CON) exercise of increasing intensity to take advantage of the fact that the rate of increase and amplitude of EMG activity are markedly greater for CON muscle actions. Seven subjects 30 ± 2 (SE) yr old performed five sets of 10 CON or ECC arm curls with each of four resistances representing 40, 60, 80, and 100% of their 10 repetition maximum for CON curls. There was 1.5 min between sets and 30 min between bouts (5 sets of 10 actions at each relative resistance) . Multiple echo, transaxial T 2 -weighted MR images (1.5 T, TR/TE 2,000/30) were collected from a 7-cm region in the middle of the arm before exercise and immediately after each bout. Surface EMG signals were collected from both heads of the biceps brachii and the long head of the triceps brachii muscles. CON and ECC actions resulted in increased integrated EMG (IEMG) and T 2 values that were strongly related (r = 0.99, P < 0.05) with relative resistance. The rate of increase and absolute value of both T 2 and IEMG were greater for CON than for ECC actions. IEMG and T 2 for both CON and ECC actions were correlated (r = 0.99, P < 0.05). The results suggest that J) surface IEMG accurately reflects the contractile behavior of muscle and 2) exercise-induced increases in MRI T 2 values reflect some processes that scale with muscle use. muscle function MAGNETIC RESONANCE SPECTROSCOPY (MRS) has become an accepted tool for in vivo biochemical studies of muscle tissue. Magnetic r esonance (MR) imaging (MRI) is a variant of this methodology that is rapidly becoming the standard for many clinical diagnostic applications because it provides unparalleled visualization of anatomic detail of soft tissues such as muscle, tendon, cartilage, and various organs. MRI has also begun to be used in basic muscle research. For example, MR images of skeletal muscle show exercise-induced contrast enhance-1578 ment, which appears to be graded with exercise intensity (7). This has been used to infer which muscles were used during the activity and the extent of their contribution.Electromyography (EMG) has long been the noninvasive method of choice for analyses of muscle activation during exercise (2). It entails sampling electrical activity from a muscle region of interest with needle or surface electrodes. There is good relation between EMG amplitude and force development for a variety of...

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Carbon-13 and proton magnetic resonance of mouse muscle

Cited by 24 publications

References 21 publications

Effects of exercise on muscle transverse relaxation determined by MR imaging and in vivo relaxometry

Effects of exercise on muscle transverse relaxation determined by MR imaging and in vivo relaxometry

Nuclear magnetic resonance transverse relaxation in muscle water

Magnetic resonance imaging and electromyography as indexes of muscle function

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