Fine structural details of human muscle fibres after fibre type specific glycogen depletion

Sjöstróm, Michael; Fridén, Jan; Ekblom, Björn

doi:10.1007/bf00489899

Cited by 33 publications

(35 citation statements)

References 25 publications

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“…We found muscle glycogen to be heterogeneously distributed within the cell in a manner similar to what has been described qualitatively previously (9,10,27,29). Schmalbruch and Kamieniecka (27) reported glycogen granules to be either closely packed in strands marking the boundaries of the myofibrils in the I-band region or to be located in rows or as single granules within the myofibrils (see Fig.…”

Section: Subcellular Locationssupporting

confidence: 85%

“…2). Sjostrom et al (29) extended these observations by reporting a third subcellular site of glycogen storage, the subsarcolemmal space. They characterized the intramuscular distribution of glycogen of their control subjects (i.e., resting) as 1) large subsarcolemmal accumulations, 2) large accumulations between the myofibrils (especially at I-band in close proximity to the mitochondria and SR), and 3) relatively smaller intramyofibrillar accumulations.…”

Section: Subcellular Locationsmentioning

confidence: 91%

“…Several investigators have found the ␤-particles to be located mainly in the subsarcolemmal and intermyofibrillar space, in close proximity to the sarcoplasmic reticulum (SR) (9,10,26,27,29). Rybicka (26) reviewed the area and clearly supported the concept that the structures commonly interpreted as particles of glycogen actually represent dynamic organelles (glycosomes), which act as independent metabolic units with specialized functions.…”

mentioning

confidence: 99%

“…Ekblom and co-workers (9,10,29) have provided most of our understanding of the compartmental distribution of skeletal muscle glycogen in humans. They used TEM to describe qualitatively the distribution of skeletal muscle glycogen in different subcellular locations, different muscle fiber types, and under different exercise conditions.…”

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confidence: 99%

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Quantification of subcellular glycogen in resting human muscle: granule size, number, and location

Marchand

Chorneyko²,

Tarnopolsky

et al. 2002

Journal of Applied Physiology

100

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Quantification of subcellular glycogen in resting human muscle: granule size, number, and location. J Appl Physiol 93: 1598-1607, 2002. First published July 12, 2002 10.1152/ japplphysiol.00585.2001.-A few qualitative investigations suggested that location of muscle glycogen (G) granules in specific sites may be associated with distinct metabolic roles. Similarly, it has been suggested that the acid-soluble and -insoluble G fractions (macro-and proglycogen, respectively) are different metabolic pools and also could exist as separate entities. We employed a transmission electron microscopic technique to quantify subcellular G particle size, number, and location in human vastus lateralis biopsies of 11 resting men. The intra-and interobserver variability for the various measures was generally Ͻ4%. Granule size and number were quantified in subcellular compartments (subsarcolemmal, intra-and intermyofibrillar). Subcellular location was critical: G was more densely concentrated in the subsarcolemmal than in the myofibrillar space, whereas the single-particle volume was greater in the latter. Single-particle diameter ranged from 10 to 44 m and followed a continuous, normal distribution. This implies that proglycogen is not a distinct entity, but rather that pro-and macroglycogen are divisions of smaller and larger molecules. These results demonstrate a compartmentalized pattern of subcellular G deposition in human skeletal muscle for both the size and density of granules.glycosome; metabolic compartments; electron microscopy; carbohydrate; glycogen regulation; proglycogen; macroglycogen SINCE THE DISCOVERY OF GLYCOGEN by Claude Bernard, numerous investigators have addressed many aspects of its metabolism. Although muscle glycogen concentration has been routinely quantified biochemically, the subcellular organization of glycogen particles has been studied much less frequently and only with qualitative, descriptive transmission electron microscopy (TEM) methods. Wanson and Drochmans (31) performed the first comprehensive description of rabbit skeletal muscle glycogen in its particulate ␤-form. Drochmans (5) had previously examined negatively stained liver glycogen by using TEM and described three glycogen structures in liver: ␣-, ␤-, and ␥-particles. The ␣-particles were the typical liver rosettes, and the ␤-particles were the 20-to 30-m spheroid units forming the ␣-rosettes. The ␥-particles were identified as 3-m subunits of both ␣-and ␤-structures. The single ␤-particles described in muscles by Wanson and Drochmans (31) corresponded in size and shape to the ␤-subunits that constituted the ␣-rosettes in liver.Scott and Still (28) proposed that particulate glycogen was not a molecule in the traditional static sense but rather a dynamic organelle. In 1970, Meyer et al. (21) were among the first to suggest that glycogen was complexed with proteins and represented a structural and functional unit of the muscle cells. Using TEM, they estimated the diameter of this glycogen particle to be 20-30 m. This value was in agree...

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Section: Subcellular Locationssupporting

confidence: 85%

Section: Subcellular Locationsmentioning

confidence: 91%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Quantification of subcellular glycogen in resting human muscle: granule size, number, and location

Marchand

Chorneyko²,

Tarnopolsky

et al. 2002

Journal of Applied Physiology

100

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“…More recently, magnetic resonance spectroscopy (proton or 13 C) has come into use (for a discussion of the advantages and disadvantages of these techniques, see Boesch, 1999;Price et al 1999). In a few studies electron microscopy has been used to estimate changes in a non-quantitative manner of both the number of glycogen granules (Sjöström et al 1982;Fridén et al 1989) and of the size of lipid droplets (Oberholzer et al 1976;Staron et al 1989). To answer the question as to the relative contribution of extramuscular v. intramuscular substrate sources for energy, in addition to the previously mentioned measurements, the amount of muscle mass engaged in the exercise has to be known, since the concentrations of substrates and metabolites in the muscle are expressed per kg muscle tissue.…”

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confidence: 99%

Skeletal muscle substrate metabolism during exercise: methodological considerations

González‐Alonso

Sacchetti³

et al. 1999

Proc. Nutr. Soc.

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fax +45 3545 7634, email cmrc@rh.dkThe aim of the present article is to evaluate critically the various methods employed in studies designed to quantify precisely skeletal muscle substrate utilization during exercise. In general, the pattern of substrate utilization during exercise can be described well from O 2 uptake measurements and the respiratory exchange ratio. However, if the aim is to quantify limb or muscle metabolism, invasive measurements have to be carried out, such as the determination of blood flow, arterio-venous (a-v) difference measurements for O 2 and relevant substrates, and biopsies of the active muscle. As many substrates and metabolites may be both taken up and released by muscle at rest and during exercise, isotopes can be used to determine uptake and/or release and also fractional uptake can be accounted for. Furthermore, the use of isotopes opens up further possibilities for the estimation of oxidation rates of various substrates. There are several methodological concerns to be aware of when studying the metabolic response to exercise in human subjects. These concerns include: (1) the muscle mass involved in the exercise is largely unknown (bicycle or treadmill). Moreover, whether the muscle sample obtained from a limb muscle and the substrate and metabolite concentrations are representative can be a problem; (2) the placement of the venous catheter can be critical, and it should be secured so that the blood sample represents blood from the active muscle with a minimum of contamination from other muscles and tissues; (3) the use of net limb glycerol release to estimate lipolysis is probably not valid (triacylglycerol utilization by muscle), since glycerol can be metabolized in skeletal muscle; (4) the precision of blood-borne substrate concentrations during exercise measured by a-v difference is hampered since they become very small due to the high blood flow. Recommendations are given in order to obtain more quantitative and conclusive data in studies investigating the regulatory mechanisms for substrate choice by muscle. Free fatty acids: Triacylglycerols: Exercise: Metabolic rate: Respiratory exchange ratioThrough the years, many approaches have been used to evaluate the contribution of carbohydrate and lipids to the increased energy requirements of skeletal muscle during exercise. Since both substrates are stored in the human body outside as well as within the muscle, another question is to what extent the intra-and extra-muscular substrate sources are utilized as a function of exercise intensity, work duration and substrate availability. Determination of the respiratory exchange ratio (RER) from the gas exchange in the lungs or the RQ from the arterial and venous concentration of blood gases can give quite a precise value for the relative contribution of carbohydrates and lipids at the whole-body level or over a limb. To determine the utilization of blood-borne substrates, i.e. the contribution of extramuscular sources, arterio-venous (a-v) differences for relevant substrates and me...

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Exercise and Muscle Glycogen Metabolism

Ørtenblad

Nielsen

Morton

et al. 2022

Physiology in Health and Disease

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Fine structural details of human muscle fibres after fibre type specific glycogen depletion

Cited by 33 publications

References 25 publications

Quantification of subcellular glycogen in resting human muscle: granule size, number, and location

Quantification of subcellular glycogen in resting human muscle: granule size, number, and location

Skeletal muscle substrate metabolism during exercise: methodological considerations

Exercise and Muscle Glycogen Metabolism

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