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      Improved spectral resolution and high reliability of in vivo 1H MRS at 7 T allow the characterization of the effect of acute exercise on carnosine in skeletal muscle

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          Abstract

          The aims of this study were to observe the behavior of carnosine peaks in human soleus (SOL) and gastrocnemius (GM) muscles following acute exercise, to determine the relaxation times and to assess the repeatability of carnosine quantification by 1H MRS at 7 T. Relaxation constants in GM and SOL were measured by a stimulated echo acquisition mode (STEAM) localization sequence. For T 1 measurement, an inversion recovery sequence was used. The repeatability of the measurement and the absolute quantification of carnosine were determined in both muscles in five healthy volunteers. For absolute quantification, an internal water reference signal was used. The effect of acute exercise on carnosine levels and resonance lines was tested in eight recreational runners/cyclists. The defined carnosine measurement protocol was applied three times – before and twice after (approximately 20 and 40 min) a 1‐h submaximal street run and additional toe‐hopping. The measured T 1 relaxation times for the C2‐H carnosine peak at 7 T were 2002 ± 94 and 1997 ± 259 ms for GM and SOL, respectively, and the T 2 times were 95.8 ± 9.4 and 81.0 ± 21.8 ms for GM and SOL, respectively. The coefficient of variation of the carnosine quantification measurement was 9.1% for GM and 6.3% for SOL, showing high repeatability, and the intraclass correlation coefficients (ICCs) of 0.93 for GM and 0.98 for SOL indicate the high reliability of the measurement. Acute exercise did not change the concentration of carnosine in the muscle, but affected the shape of the resonance lines, in terms of the shifting and splitting into doublets. Carnosine measurement by 1H MRS at 7 T in skeletal muscle exhibits high repeatability and reliability. The observed effects of acute exercise were more prominent in GM, probably as a result of the larger portion of glycolytic fibers in this muscle and the more pronounced exercise‐induced change in pH. Our results support the application of the MRS‐based assessment of carnosine for pH measurement in muscle compartments. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

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          A New Method for Non-Invasive Estimation of Human Muscle Fiber Type Composition

          Background It has been established that excellence in sports with short and long exercise duration requires a high proportion of fast-twitch (FT) or type-II fibers and slow-twitch (ST) or type-I fibers, respectively. Until today, the muscle biopsy method is still accepted as gold standard to measure muscle fiber type composition. Because of its invasive nature and high sampling variance, it would be useful to develop a non-invasive alternative. Methodology Eighty-three control subjects, 15 talented young track-and-field athletes, 51 elite athletes and 14 ex-athletes volunteered to participate in the current study. The carnosine content of all 163 subjects was measured in the gastrocnemius muscle by proton magnetic resonance spectroscopy (1H-MRS). Muscle biopsies for fiber typing were taken from 12 untrained males. Principal Findings A significant positive correlation was found between muscle carnosine, measured by 1H-MRS, and percentage area occupied by type II fibers. Explosive athletes had ∼30% higher carnosine levels compared to a reference population, whereas it was ∼20% lower than normal in typical endurance athletes. Similar results were found in young talents and ex-athletes. When active elite runners were ranked according to their best running distance, a negative sigmoidal curve was found between logarithm of running distance and muscle carnosine. Conclusions Muscle carnosine content shows a good reflection of the disciplines of elite track-and-field athletes and is able to distinguish between individual track running distances. The differences between endurance and sprint muscle types is also observed in young talents and former athletes, suggesting this characteristic is genetically determined and can be applied in early talent identification. This quick method provides a valid alternative for the muscle biopsy method. In addition, this technique may also contribute to the diagnosis and monitoring of many conditions and diseases that are characterized by an altered muscle fiber type composition.
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            Fibre type composition of soleus and extensor digitorum longus muscles in normal female inbred Lewis rats.

            We have analysed the fibre type composition of soleus and extensor digitorum longus (EDL) muscles of normal female 4-6-month-old inbred Lewis rats. This rat strain is used in our ongoing study of the effects of thyroid hormone on myosin heavy chain (MyHC) isoform expression. On the basis of the mATPase reaction, soleus muscles contained 96.1 +/- 2.9% of type 1 fibres supplemented by 2A fibres. EDL muscles contained type 1 (5.5 +/- 1.0%), type 2A (18.8 +/- 1.7%) and type 2B (75.7 +/- 2.2%) fibres. Immunohistochemical analysis and SDS gel electrophoresis confirmed that most fibres in the soleus muscle expressed the type 1 (slow) MyHC isoform and that only a small proportion of fibres expressed the fast 2a MyHC isoform. Immunohistochemical analysis and SDS gel electrophoresis demonstrated that almost half of the 2B fibres of EDL muscles expressed the 2x/d MyHC isoform. In both muscle types, many fibres expressed more than one MyHC isoform. The content of slow fibres in the soleus muscle of female inbred Lewis rats was slightly higher than that reported for Wistar rats, but was considerably higher than that of Sprague-Dawley rats, whereas substantial differences were not found in the proportion of slow and fast fibre types in EDL muscles in these strains.
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              Carnosine and anserine concentrations in the quadriceps femoris muscle of healthy humans.

              The content of anserine and carnosine in the lateral portion of the quadriceps femoris muscle of 50 healthy, human subjects has been studied. Anserine was undetectable in all muscle samples examined. Muscle carnosine values for the group conformed to a normal distribution with a mean (SD) value of 20.0 (4.7) mmol.kg-1 of dry muscle mass. The concentration of carnosine was significantly higher in the muscle of male subjects (21.3, 4.2 mmol.kg-1 dry mass) than in females of a similar age and training status (17.5, 4.8 mmol.kg-1 dry mass) (P less than 0.005). The test-retest reliability of measures was determined on a subgroup of 17 subjects. No significant difference in mean carnosine concentration was found between the two trials [21.5 (4.0) and 22.0 (5.2) mmol.kg-1 dry muscle mass; P greater than 0.05]. The importance of carnosine as a physicochemical buffer within human muscle was examined by calculating its buffering ability over the physiological pH range. From the range of carnosine concentrations observed (7.2-30.7 mmol.kg-1 dry muscle mass), it was estimated that the dipeptide could buffer between 2.4 and 10.1 mmol H+.kg-1 dry mass over the physiological pH range 7.1-6.5, contributing, on average, approximately 7% to the total muscle buffering. This suggests that in humans, in contrast to many other species, carnosine is of only limited importance in preventing the reduction in pH observed during high intensity exercise.
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                Author and article information

                Journal
                NMR Biomed
                NMR Biomed
                10.1002/(ISSN)1099-1492
                NBM
                Nmr in Biomedicine
                John Wiley and Sons Inc. (Hoboken )
                0952-3480
                1099-1492
                29 November 2015
                January 2016
                : 29
                : 1 ( doiID: 10.1002/nbm.v29.1 )
                : 24-32
                Affiliations
                [ 1 ] High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of Vienna ViennaAustria
                [ 2 ]Christian Doppler Laboratory for Clinical Molecular MR Imaging ViennaAustria
                [ 3 ] Department of Imaging MethodsInstitute of Measurement Science, Slovak Academy of Sciences BratislavaSlovakia
                [ 4 ] Oxford Centre for Clinical Magnetic Resonance Research (OCMR)University of Oxford OxfordUK
                [ 5 ] Obesity Section, Diabetes and Metabolic Disease LaboratoryInstitute of Experimental Endocrinology, Slovak Academy of Sciences BratislavaSlovakia
                [ 6 ] Monash Centre for Health, Research and ImplementationSchool of Public Health and Preventive Medicine MelbourneAustralia
                [ 7 ] School of MedicineCommenius University Bratislava BratislavaSlovakia
                [ 8 ] Division of Endocrinology and Metabolism, Department of Internal Medicine IIIMedical University of Vienna ViennaAustria
                Author notes
                [*] [* ] Correspondence to: M. Krššák, Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18–20, A‐1090 Vienna, Austria.

                E‐mail: martin.krssak@ 123456meduniwien.ac.at

                Article
                NBM3447 NBM-15-0071.R2
                10.1002/nbm.3447
                4737290
                26615795
                1566126d-087c-4dc0-8af3-ad3a82988ce1
                © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

                This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

                History
                : 12 March 2015
                : 20 October 2015
                : 21 October 2015
                Page count
                Pages: 9
                Categories
                Research Article
                Research Articles
                Custom metadata
                2.0
                nbm3447
                January 2016
                Converter:WILEY_ML3GV2_TO_NLMPMC version:4.7.6 mode:remove_FC converted:02.02.2016

                Radiology & Imaging
                carnosine,1h mrs,7 t,skeletal muscle,acute exercise,relaxation times,repeatability
                Radiology & Imaging
                carnosine, 1h mrs, 7 t, skeletal muscle, acute exercise, relaxation times, repeatability

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