Function, morphology and protein expression of ageing skeletal muscle: a cross‐sectional study of elderly men with different training backgrounds

Klitgaard, Henrik; Mantoni, Margit; Schiaffino, Stefano; Ausoni, Simonetta; Gorza, Luisa; Laurent‐Winter, Christine; Schnohr, Peter; Saltin, Bengt

doi:10.1111/j.1748-1716.1990.tb08974.x

Cited by 491 publications

(415 citation statements)

References 37 publications

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“…However, large-scale histochemical studies agree that a noticeably higher loss in type II fibres occurs as compared to slower twitching type I fibres (Vandervoort, 2002). The proteomic identification of MLC-2 as being a contractile element with an increased abundance in aged muscle fibres is in agreement with a previous histochemical study by Klitgaard et al (1990). This makes the slow-type MLC-2 protein species a potentially useful indicator of the fast-to-slow transformation process in senescent muscles.…”

Section: Discussionsupporting

confidence: 88%

Drastic increase of myosin light chain MLC-2 in senescent skeletal muscle indicates fast-to-slow fibre transition in sarcopenia of old age

Gannon

Doran

Kirwan

et al. 2009

European Journal of Cell Biology

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The age-dependent decline in skeletal muscle mass and function is believed to be due to a multi-factorial pathology and represents a major factor that blocks healthy aging by increasing physical disability, frailty and loss of independence in the elderly. This study has focused on the comparative proteomic analysis of contractile elements and revealed that the most striking age-related changes seem to occur in the protein family representing myosin light chains (MLCs). Comparative screening of total muscle extracts suggests a fast-to-slow transition in the aged MLC population. The mass spectrometric analysis of the myofibril-enriched fraction identified the MLC2 isoform of the slow-type MLC as the contractile protein with the most drastically changed expression during aging. Immunoblotting confirmed an increased abundance of slow MLC2, concomitant with a switch in fast versus slow myosin heavy chains. Staining of two-dimensional gels of crude extracts with the phospho-specific fluorescent dye ProQ-Diamond identified the increased MLC2 spot as a muscle protein with a drastically enhanced phosphorylation level in aged fibres. Comparative immunofluorescence microscopy, using antibodies to fast and slow myosin isoforms, confirmed a fast-to-slow transformation process during muscle aging. Interestingly, the dramatic increase in slow MLC2 expression was restricted to individual senescent fibres. These findings agree with the idea that aged skeletal muscles undergo a shift to more aerobic-oxidative metabolism in a slower-twitching fibre population and suggest the slow MLC2 isoform as a potential biomarker for fibre type shifting in sarcopenia of old age.

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Section: Discussionsupporting

confidence: 88%

Drastic increase of myosin light chain MLC-2 in senescent skeletal muscle indicates fast-to-slow fibre transition in sarcopenia of old age

Gannon

Doran

Kirwan

et al. 2009

European Journal of Cell Biology

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“…18 The homogenates were loaded on SDS ± PAGE (sodium dodecyl sulphate poly acryl amide gel electrophoresis) gels containing 37.5% glycerol and 6% polyacrylamide. Electrophoresis was performed for 18 ± 20 h at 70 V followed by 3 ± 5 h at 200 V. 19 The gels were subsequently silver-stained (Gelcode color silver stain, Pierce). The relative proportions of the three distinct bands (MHC I, IIA and IIB) were analyzed on a computer-integrated densitometer (Cream 1-D, Kem-En-Tec Aps, Copenhagen, Denmark).…”

Section: Muscular Microstructurementioning

confidence: 99%

Long term adaptation to electrically induced cycle training in severe spinal cord injured individuals

et al. 1997

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Spinal cord injured (SCI) individuals most often contract their injury at a young age and are deemed to a life of more or less physical inactivity. In addition to the primary implications of the SCI, severe SCI individuals are stigmatized by conditions related to their physically inactive lifestyle. It is unknown if these inactivity related conditions are potentially reversible and the aim of the present study was, therefore, to examine the e ect of exercise on SCI individuals. Ten such individuals (six with tetraplegia and four with paraplegia; age 27 ± 45 years; time since injury 3 ± 23 years) were exercise trained for 1 year using an electrically induced computerized feedback controlled cycle ergometer. They trained for up to three times a week (mean 2.3 times), 30 min on each occasion. The gluteal, hamstring and quadriceps muscles were stimulated via electrodes placed on the skin over their motor points. During the ®rst training bouts, a substantial variation in performance was seen between the subjects. A majority of them were capable of performing 30 min of exercise in the ®rst bout; however, two individuals were only able to perform a few minutes of exercise. After training for 1 year all of the subjects were able to perform 30 min of continuous training and the work output had increased from 4+1 (mean+SE) to 17+2 Kilo Joules per training bout (P50.05). The maximal oxygen uptake during electrically induced exercise increased from 1.20+0.08 litres per minute measured after a few weeks habituation to the exercise to 1.43+0.09 litres per minute after training for 1 year (P50.05).Magnetic resonance cross sectional images of the thigh were performed to estimate muscle mass and an increase of 12% (mean, P50.05) was seen in response to 1 year of training. In biopsies taken before exercise various degrees of atrophy were observed in the individual muscle ®bres, a phenomenon that was partially normalized in all subjects after training.The ®bre type distribution in skeletal muscles is known to shift towards type IIB ®bres (fast twitch, fast fatiguable, glycolytic ®bres) within the ®rst 2 years after the spinal cord injury. The muscle in the present investigation contained of 63% myosin heavy chain (MHC) isoform IIB, 33% MHC isoform IIA (fast twitch, fatigue resistant) and less than 5% MHC isoform I (slow twitch) before training. A shift towards more fatigue resistant contractile proteins was found after 1 year of training. The percentage of MHC isoform IIA increased to 61% of all contractile protein and a corresponding decrease to 32% was seen in the fast fatiguable MHC isoform IIB, whereas MHC isoform I only comprised 7% of the total amount of MHC. This shift was accompanied by a doubling of the enzymatic activity of citrate synthase, as an indicator of mitochondrial oxidative capacity.It is concluded that inactivity-associated changes in exercise performance capacity and skeletal muscle occurring in SCI individuals after injury are reversible, even up to over 20 years after the injury. It follows that electricall...

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“…As it has been known for many years that strength training is quite effective in restoring the age-related losses in muscle mass and function (8)(9)(10) it is generally assumed that the main determinant of sarcopenia appears to be the decline in resistance-type physical activities (8,(11)(12)(13)(14)(15) . While the atrophy of disuse, such as occurs with protracted bed rest is well described (8,10,16) it is less clear cut as to the extent to which variation in levels of physical activity within the normal population influences sarcopenia, mainly because of the difficulty of measurement.…”

Section: Inactivity: Energy Intakesmentioning

confidence: 99%

Nutrition and sarcopenia: evidence for an interaction

Millward

2012

Proc. Nutr. Soc.

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Nutritional interventions that might influence sarcopenia, as indicated by literature reporting on sarcopenia per se as well as dynapenia and frailty, are reviewed in relation to potential physiological aetiological factors, i.e. inactivity, anabolic resistance, inflammation, acidosis and vitamin D deficiency. As sarcopenia occurs in physically active and presumably well-nourished populations, it is argued that a simple nutritional aetiology is unlikely and unequivocal evidence for any nutritional influence is extremely limited. Dietary protein is probably the most widely researched nutrient but only for frailty is there one study showing evidence of an aetiological influence and most intervention studies with protein or amino acids have proved ineffective with only a very few exceptions. Fish oil has been shown to attenuate anabolic resistance of muscle protein synthesis in one study. There is limited evidence for a protective influence of antioxidants and inducers of phase 2 proteins on sarcopenia, dynapenia and anabolic resistance in human and animal studies. Also fruit and vegetables may protect against acidosis-induced sarcopenia through their provision of dietary potassium. While severe vitamin D deficiency is associated with dynapenia and sarcopenia, the evidence for a beneficial influence of increasing vitamin D status above the severe deficiency level is limited and controversial, especially in men. On this basis there is insufficient evidence for any more specific nutritional advice than that contained in the general healthy lifestyle-healthy diet message: i.e. avoiding inactivity and low intakes of food energy and nutrients and maintain an active lifestyle with a diet providing a rich supply of fruit and vegetables and frequent oily fish. Aging: Dynapenia: Inactivity: Anabolic resistance: DietIn a recent consensus paper sarcopenia (1) was defined as the age-associated loss of skeletal muscle mass and function, a complex syndrome associated with muscle mass loss alone or in conjunction with increased fat mass. It was argued that although cachexia may be a component of sarcopenia, the two conditions are not the same. What was not discussed in this paper was the difference between sarcopenia and dynapenia which is important in terms of the clinical relevance of the condition. Thus Jansonn (2) points out that the data on the functional implications of sarcopenia are inconsistent, possibly because we do not always recognise the distinction between sarcopenia, loss of muscle mass and dynapenia and loss of muscle strength. These, he argues, are physiologically different with dynapenia the main predictor of functional impairment and/or physical disability, chronic disease and mortality risk, to the extent that research and clinical emphasis should be placed more on dynapenia than on sarcopenia. In fact this argument can, to some extent be extended to include frailty, a much more general term for a collection

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Function, morphology and protein expression of ageing skeletal muscle: a cross‐sectional study of elderly men with different training backgrounds

Cited by 491 publications

References 37 publications

Drastic increase of myosin light chain MLC-2 in senescent skeletal muscle indicates fast-to-slow fibre transition in sarcopenia of old age

Drastic increase of myosin light chain MLC-2 in senescent skeletal muscle indicates fast-to-slow fibre transition in sarcopenia of old age

Long term adaptation to electrically induced cycle training in severe spinal cord injured individuals

Nutrition and sarcopenia: evidence for an interaction

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