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Tabozzi SA, Stancari G, Zucca E, Tajoli M, Stucchi L, Lafortuna CL, Ferrucci F. Variation of skeletal muscle ultrasound imaging intensity in horses after treadmill exercise: a proof of concept for glycogen content estimation. BMC Vet Res 2021; 17:121. [PMID: 33726767 PMCID: PMC7962389 DOI: 10.1186/s12917-021-02818-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 02/25/2021] [Indexed: 11/10/2022] Open
Abstract
Background Glycogen in skeletal muscle is a major source of energy during exercise and an important determinant of endurance capacity, so that its measurement may provide a meaningful marker of athletes’ preparation and a possible predictor of performance, both in humans and in equines. Gold standard of glycogen concentration measurement is the histochemical and biochemical analysis of biopsy-derived muscle tissue, an invasive and potentially injuring procedure. Recently, high-frequency ultrasound (US) technology is being exploited in human sports medicine to estimate muscle glycogen content. Therefore, aim of the present study is to evaluate the feasibility of US assessment of muscle glycogen in equines. Results US images of gluteus medius (GL) and semitendinosus (ST) muscles were obtained on eight healthy horses (3–10 years) before and after a steady-state exercise on treadmill (velocity: 4.0–12.5 m/s; duration: 2–20 min; heart rate: 137–218 b/min). Average image greyscale intensity was significantly different between GL and ST, both before and after exercise (p < 0.001). Comparing baseline and post-exercise US images, significant increase in greyscale intensity has been observed in ST (p < 0.001), but not in GL (p = 0.129). The volume of the exercise was significantly correlated with exercise-dependent change in image intensity (R2 = 0.891), consistent with a reduction of glycogen muscle stores resulting from aerobic activity. Conclusions US technique evidences also in horses muscle changes possibly associated to glycogen utilisation during exercise. Present results on a small sample need to be further confirmed and provide preliminary data warranting future validation by direct glycogen measurement through biopsy technique.
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Affiliation(s)
- Sarah A Tabozzi
- Present Address: Croce Rossa Italiana, Comitato Nazionale, Via Ramazzini 37, Roma, Italy.
| | - Giovanni Stancari
- Laboratorio di Medicina Sportiva del Cavallo "Franco Tradati", Università degli Studi di Milano, Lodi, Italy
| | - Enrica Zucca
- Laboratorio di Medicina Sportiva del Cavallo "Franco Tradati", Università degli Studi di Milano, Lodi, Italy
| | - Michela Tajoli
- Laboratorio di Medicina Sportiva del Cavallo "Franco Tradati", Università degli Studi di Milano, Lodi, Italy
| | - Luca Stucchi
- Laboratorio di Medicina Sportiva del Cavallo "Franco Tradati", Università degli Studi di Milano, Lodi, Italy
| | | | - Francesco Ferrucci
- Laboratorio di Medicina Sportiva del Cavallo "Franco Tradati", Università degli Studi di Milano, Lodi, Italy
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Klein DJ, McKeever KH, Mirek ET, Anthony TG. Metabolomic Response of Equine Skeletal Muscle to Acute Fatiguing Exercise and Training. Front Physiol 2020; 11:110. [PMID: 32132934 PMCID: PMC7040365 DOI: 10.3389/fphys.2020.00110] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 01/30/2020] [Indexed: 12/22/2022] Open
Abstract
The athletic horse, despite being over 50% muscle mass, remains understudied with regard to the effects of exercise and training on skeletal muscle metabolism. To begin to address this knowledge gap, we employed an untargeted metabolomics approach to characterize the exercise-induced and fitness-related changes in the skeletal muscle of eight unconditioned Standardbred horses (four male, four female) before and after a 12-week training period. Before training, unconditioned horses showed a high degree of individual variation in the skeletal muscle metabolome, resulting in very few differences basally and at 3 and 24 h after acute fatiguing exercise. Training did not alter body composition but did improve maximal aerobic and running capacities (p < 0.05), and significantly altered the skeletal muscle metabolome (p < 0.05, q < 0.1). While sex independently influenced body composition and distance run following training (p < 0.05), sex did not affect the skeletal muscle metabolome. Exercise-induced metabolomic alterations (p < 0.05, q < 0.1) largely centered on the branched-chain amino acids (BCAA), xenobiotics, and a variety of lipid and nucleotide-related metabolites, particularly in the conditioned state. Further, training increased (p < 0.05, q < 0.1) the relative abundance of almost every identified lipid species, and this was accompanied by increased plasma BCAAs (p < 0.0005), phenylalanine (p = 0.01), and tyrosine (p < 0.02). Acute exercise in the conditioned state decreased (p < 0.05, q < 0.1) the relative abundance of almost all lipid-related species in skeletal muscle by 24 h post-exercise, whereas plasma amino acids remained unaltered. These changes occurred alongside increased muscle gene expression (p < 0.05) related to lipid uptake (Cd36) and lipid (Cpt1b) and BCAA (Bckdk) utilization. This work suggests that metabolites related to amino acid, lipid, nucleotide and xenobiotic metabolism play pivotal roles in the response of equine skeletal muscle to vigorous exercise and training. Use of these and future data sets could be used to track the impact of training and fitness on equine health and may lead to novel predictors and/or diagnostic biomarkers.
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Affiliation(s)
- Dylan J Klein
- Department of Health and Exercise Science, Rowan University, Glassboro, NJ, United States
| | - Kenneth H McKeever
- Rutgers Equine Science Center, Department of Animal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Emily T Mirek
- Department of Nutritional Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Tracy G Anthony
- Department of Nutritional Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States.,New Jersey Institute for Food, Nutrition, and Health, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
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Bryan K, Katz L, Hill E. Effects of equine myostatin (MSTN) genotype variation on transcriptional responses in Thoroughbred skeletal muscle. COMPARATIVE EXERCISE PHYSIOLOGY 2019. [DOI: 10.3920/cep190009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Myostatin gene (MSTN) variation influences distance aptitude in Thoroughbreds as a consequence of functional physiological effects including skeletal muscle fibre type and muscle hypertrophy variation. A promotor region short interspersed nuclear element (SINE) insertion, tagged by SNP g.66493737-C, alters MSTN mRNA expression. We tested the hypothesis that skeletal muscle gene expression varies among MSTN genotypes due to differential up- or down-stream gene signalling pathways that may be influenced by exercise and training and consequently contribute to variation in exercise phenotypes. Skeletal muscle biopsies were collected from Thoroughbreds previously genotyped for MSTN (n=35 CC, n=50 CT, n=9 TT) at three different time-points: untrained at rest (UR), untrained after exercise (UE) and trained at rest (TR). Gene differential expression (DE) was determined from RNAseq data using DESeq2 (Benjamini-Hochberg P-value <0.05). Functional over-representation analysis was performed in DAVID. In UR samples, one, nine and 47 genes were DE between CC vs CT, CT vs TT and C:C vs TT, respectively. The OSGEPL1 gene, located <250 Kb proximal to MSTN, was DE among all cohorts. Six genes were DE in UE between CC vs TT including OSGEPL1, FGF10 and COQ8A. There was significant enrichment for GO categories related to mitochondria in TR. Comparison of the exercise response (UR vs UE) revealed patterns of expression that were opposing; i.e. CHRNG was 0.857 log2FC in the TT cohort but 2.055 log2FC in the CC cohort. Genes located in proximity to MSTN and involved in mitochondrial function were most significantly different among genotype cohorts. Patterns of DE among genotypes suggests gene-regulated influence on the phenotype. Understanding these patterns may assist genotype-guided training strategies.
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Affiliation(s)
- K. Bryan
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8, Ireland
| | - L.M. Katz
- UCD School of Veterinary Medicine, University College Dublin, Belfield, D04 V1W8, Ireland
| | - E.W. Hill
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8, Ireland
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McKenzie E. Foundations of performance – factors that contribute to excellence in equine exercise. COMPARATIVE EXERCISE PHYSIOLOGY 2017. [DOI: 10.3920/cep170022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Horses are renowned for their incredible capacity for a range of athletic activities, and participation in athletic events arguably represents the most critical strut of the equine industry. Successful performance is typically a primary focus during participation in competitive athletic events, and relies upon a variety of innate physiological and structural factors of the athlete. However, a wide range of external factors also influence performance, and many of these can be readily manipulated. Therefore, thorough assessment of the individual’s inherent capacity for a specific athletic discipline must be combined with optimisation of external factors including nutrition and training to promote excellent performance. Recent progress in methods of athlete selection and monitoring of training responses are assisting continued improvements in equine performance.
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Affiliation(s)
- E. McKenzie
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, 227 Magruder Hall, Corvallis, OR 97331, USA
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Bryan K, McGivney BA, Farries G, McGettigan PA, McGivney CL, Gough KF, MacHugh DE, Katz LM, Hill EW. Equine skeletal muscle adaptations to exercise and training: evidence of differential regulation of autophagosomal and mitochondrial components. BMC Genomics 2017; 18:595. [PMID: 28793853 PMCID: PMC5551008 DOI: 10.1186/s12864-017-4007-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 08/02/2017] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND A single bout of exercise induces changes in gene expression in skeletal muscle. Regular exercise results in an adaptive response involving changes in muscle architecture and biochemistry, and is an effective way to manage and prevent common human diseases such as obesity, cardiovascular disorders and type II diabetes. However, the biomolecular mechanisms underlying such responses still need to be fully elucidated. Here we performed a transcriptome-wide analysis of skeletal muscle tissue in a large cohort of untrained Thoroughbred horses (n = 51) before and after a bout of high-intensity exercise and again after an extended period of training. We hypothesized that regular high-intensity exercise training primes the transcriptome for the demands of high-intensity exercise. RESULTS An extensive set of genes was observed to be significantly differentially regulated in response to a single bout of high-intensity exercise in the untrained cohort (3241 genes) and following multiple bouts of high-intensity exercise training over a six-month period (3405 genes). Approximately one-third of these genes (1025) and several biological processes related to energy metabolism were common to both the exercise and training responses. We then developed a novel network-based computational analysis pipeline to test the hypothesis that these transcriptional changes also influence the contextual molecular interactome and its dynamics in response to exercise and training. The contextual network analysis identified several important hub genes, including the autophagosomal-related gene GABARAPL1, and dynamic functional modules, including those enriched for mitochondrial respiratory chain complexes I and V, that were differentially regulated and had their putative interactions 're-wired' in the exercise and/or training responses. CONCLUSION Here we have generated for the first time, a comprehensive set of genes that are differentially expressed in Thoroughbred skeletal muscle in response to both exercise and training. These data indicate that consecutive bouts of high-intensity exercise result in a priming of the skeletal muscle transcriptome for the demands of the next exercise bout. Furthermore, this may also lead to an extensive 're-wiring' of the molecular interactome in both exercise and training and include key genes and functional modules related to autophagy and the mitochondrion.
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Affiliation(s)
- Kenneth Bryan
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Beatrice A. McGivney
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Gabriella Farries
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Paul A. McGettigan
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Charlotte L. McGivney
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Katie F. Gough
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
| | - David E. MacHugh
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Lisa M. Katz
- UCD School of Veterinary Medicine, University College Dublin, Belfield, D04 V1W8 Ireland
| | - Emmeline W. Hill
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, D04 V1W8 Ireland
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Current Knowledge of Pathologic Mechanisms and Derived Practical Applications to Prevent Metabolic Disturbances and Exhaustion in the Endurance Horse. J Equine Vet Sci 2017. [DOI: 10.1016/j.jevs.2016.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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McKenzie E, Eyrich L, Payton M, Valberg S. Clinical, histopathological and metabolic responses following exercise in Arabian horses with a history of exertional rhabdomyolysis. Vet J 2016; 216:196-201. [DOI: 10.1016/j.tvjl.2016.08.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 08/16/2016] [Accepted: 08/18/2016] [Indexed: 11/16/2022]
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Expression and regulation of facilitative glucose transporters in equine insulin-sensitive tissue: from physiology to pathology. ISRN VETERINARY SCIENCE 2014; 2014:409547. [PMID: 24977043 PMCID: PMC4060548 DOI: 10.1155/2014/409547] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/09/2013] [Indexed: 01/12/2023]
Abstract
Glucose uptake is the rate-limiting step in glucose utilization in mammalians and is tightly regulated by a family of specialized proteins, called the facilitated glucose transporters (GLUTs/SLC2). GLUT4, the major isoform in insulin-responsive tissue, translocates from an intracellular pool to the cell surface and as such determines insulin-stimulated glucose uptake. However, despite intensive research over 50 years, the insulin-dependent and -independent pathways that mediate GLUT4 translocation are not fully elucidated in any species. Insulin resistance (IR) is one of the hallmarks of equine metabolic syndrome and is the most common metabolic predisposition for laminitis in horses. IR is characterized by the impaired ability of insulin to stimulate glucose disposal into insulin-sensitive tissues. Similar to other species, the functional capability of the insulin-responsive GLUTs is impaired in muscle and adipose tissue during IR in horses. However, the molecular mechanisms of altered glucose transport remain elusive in all species, and there is still much to learn about the physiological and pathophysiological functions of the GLUT family members, especially in regard to class III. Since GLUTs are key regulators of whole-body glucose homeostasis, they have received considerable attention as potential therapeutic targets to treat metabolic disorders in human and equine patients.
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McKenzie E, Esser M, Payton M. Serum biochemistry changes in horses racing a multiday endurance event. COMPARATIVE EXERCISE PHYSIOLOGY 2014. [DOI: 10.3920/cep140017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Endurance competition frequently provokes serum biochemistry alterations in horses racing single day events. This study assessed the effect of consecutive days of endurance racing on commonly analysed serum biochemistry variables of horses. Blood was obtained once before 54 horses commenced racing 40 km or 80 km/day, and 4-6 h after horses finished each day of racing. Data were analysed via repeated measures ANOVA (P<0.05, mean ± standard error). Ten horses completed 40 km once, and 44, 18 and 9 horses completed one, two and three consecutive 80 km days, respectively, with valid results obtained for 41 of the 44 horses. Before racing, all variables were within reference intervals in both groups. After one day of racing, serum urea nitrogen and magnesium were higher in horses racing 80 km compared to 40 km, and total CO2 was lower. In both groups, total protein and globulin decreased after racing, and creatine kinase increased, exceeding the reference interval in the 80 km group on day one and two of racing. Within the 80 km group, serum urea nitrogen, creatinine, phosphorus and bilirubin were slightly higher on all race days than before racing, and serum glucose exceeded reference interval on day one of racing. Serum albumin was slightly lower on day two and three of racing, and aspartate transaminase was higher and exceeded reference interval on all race days. No significant changes occurred in sodium, potassium, chloride, calcium or magnesium concentrations in either category. Subset analysis of valid results from six horses that raced three consecutive 80 km days revealed similar changes in serum urea nitrogen, phosphorus, total protein, albumin, globulin, and muscle enzymes with racing. This study identified mild serum biochemistry changes in horses racing 80 km/day for up to three consecutive days, suggesting that non-elite multiday endurance competition is well tolerated.
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Affiliation(s)
- E.C. McKenzie
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, 700 SW 30th Street, Corvallis, OR 97331, USA
| | - M.M. Esser
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, 700 SW 30th Street, Corvallis, OR 97331, USA
- University of Minnesota Saint Paul, Room 225 VMC, 1365 Gortner Ave, St Paul, MN 55108, USA
| | - M.E. Payton
- Department of Statistics, Oklahoma State University, 301 MSCS, Stillwater, OK 74078, USA
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Westermann CM, Dorland L, van Diggelen OP, Schoonderwoerd K, Bierau J, Waterham HR, van der Kolk JH. Decreased oxidative phosphorylation and PGAM deficiency in horses suffering from atypical myopathy associated with acquired MADD. Mol Genet Metab 2011; 104:273-8. [PMID: 21843962 DOI: 10.1016/j.ymgme.2011.07.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 11/27/2022]
Abstract
Earlier research on ten horses suffering from the frequently fatal disorder atypical myopathy showed that MADD (multiple acyl-CoA dehydrogenase deficiency) is the biochemical derangement behind atypical myopathy. From five horses that died as a result of this disease and seven healthy control horses, urine and plasma were collected ante mortem and muscle biopsies were obtained immediately post-mortem (2 patients and 7 control horses), to analyse creatine, purine and carbohydrate metabolism as well as oxidative phosphorylation. In patients, the mean creatine concentration in urine was increased 17-fold and the concentration of uric acid approximately 4-fold, compared to controls. The highest degree of depletion of glycogen was observed in the patient with the most severe myopathy clinically. In this patient, glycolysis was more active than in the other patients and controls, which may explain this depletion. One patient demonstrated very low phosphoglycerate mutase (PGAM) activity, less than 10% of reference values. Most respiratory chain complex activity in patients was 20-30% lower than in control horses, complex II activity was 42% lower than normal, and one patient had severely decrease ATP-synthase activity, more than 60% lower than in control horses. General markers for myopathic damage are creatine kinase (CK) and lactic acid in plasma, and creatine and uric acid in urine. To obtain more information about the cause of the myopathy analysis of carbohydrate, lipid and protein metabolism as well as oxidative phosphorylation is advised. This study expands the diagnostic possibilities of equine myopathies.
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Affiliation(s)
- C M Westermann
- Department of Equine Sciences, Medicine Section, Faculty of Veterinary Medicine, Yalelaan 114, 3584 CM, Utrecht University, Utrecht, The Netherlands.
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Lacombe VA. Glucose metabolism in insulin-sensitive tissue: from health to disease and Glucose Transport in Adipose Tissue: Novel Insights into the Pathogenesis of Insulin Resistance. J Equine Vet Sci 2011. [DOI: 10.1016/j.jevs.2011.09.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Caiado JC, Pissinate GL, Souza VR, Fonseca LA, Coelho CS. Lactacidemia e concentrações séricas de aspartato aminotransferase e creatinoquinase em equinos da raça Quarto de Milha usados em provas de laço em dupla. PESQUISA VETERINARIA BRASILEIRA 2011. [DOI: 10.1590/s0100-736x2011000500014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
O presente estudo teve por objetivo avaliar a influência do exercício físico de alta intensidade e curta duração (provas de laço em dupla) sobre a lactacidemia e as concentrações séricas de aspartato aminotransferase (AST) e creatinoquinase (CK) em equinos durante competição realizada no estado do Espírito Santo. Para tal foram obtidas amostras de soro e plasma de 20 equinos, da raça Quarto de Milha ou mestiços, em três momentos assim definidos: no repouso, uma semana antes da prova atlética, já com o animal em treinamento (T0); antes da prova atlética (T1) e imediatamente após o término da mesma (T2). As referidas amostras foram encaminhadas ao Laboratório Clínico do Centro Universitário Vila Velha (UVV) para as análises. Na avaliação da lactacidemia, os resultados registrados nos momentos T0, T1 e T2 foram, respectivamente, de 0,49±0,24mmol/L, 0,93±0,16mmol/L e 9,86±2,09mmol/L. Na avaliação da atividade sérica de AST, os resultados registrados nos momentos T0, T1e T2 foram, respectivamente, de 189,1±43,6 UI/L, 210,2±46,7 UI/L e 173,1±33,5 UI/L. Por fim, a avaliação da atividade sérica da CK nos momentos T0,T1 e T2 foram,respectivamente, de 110,9±35,2 UI/L, 51,8±15,4 UI/L e 88,2±33,5 UI/L. A análise dos resultados demonstrou que o exercício físico imposto levou ao aumento significativo de lactato plasmático e CK sérica e não alterou o AST sérico e que a interpretação destes resultados permitiu concluir que os equinos usados estavam aptos ao nível de exercício físico imposto.
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Waller AP, Burns TA, Mudge MC, Belknap JK, Lacombe VA. Insulin resistance selectively alters cell-surface glucose transporters but not their total protein expression in equine skeletal muscle. J Vet Intern Med 2011; 25:315-21. [PMID: 21314720 DOI: 10.1111/j.1939-1676.2010.0674.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Insulin resistance (IR) has been widely recognized in humans, and more recently in horses, but its underlying mechanisms are still not well understood. The translocation of glucose transporter 4 (GLUT4) to the cell surface is the limiting step for glucose uptake in insulin-sensitive tissues. Although the downstream signaling pathways regulating GLUT translocation are not well defined, AS160 recently has emerged as a potential key component. In addition, the role of GLUT12, one of the most recently identified insulin-sensitive GLUTs, during IR is unknown. HYPOTHESIS/OBJECTIVES We hypothesized that cell-surface GLUT will be decreased in muscle by an AS160-dependent pathway in horses with IR. ANIMALS Insulin-sensitive (IS) or IR mares (n = 5/group). METHODS Muscle biopsies were performed in mares classified as IS or IR based on results of an insulin-modified frequently sampled IV glucose tolerance test. By an exofacial bis-mannose photolabeled method, we specifically quantified active cell-surface GLUT4 and GLUT12 transporters. Total GLUT4 and GLUT12 and AS160 protein expression were measured by Western blots. RESULTS IR decreased basal cell-surface GLUT4 expression (P= .027), but not GLUT12, by an AS160-independent pathway, without affecting total GLUT4 and GLUT12 content. Cell-surface GLUT4 was not further enhanced by insulin stimulation in either group. CONCLUSIONS AND CLINICAL IMPORTANCE IR induced defects in the skeletal muscle glucose transport pathway by decreasing active cell-surface GLUT4.
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Affiliation(s)
- A P Waller
- College of Pharmacy, The Ohio State University, Columbus, OH, USA
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15
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Waller AP, Lindinger MI. Nutritional aspects of post exercise skeletal muscle glycogen synthesis in horses: a comparative review. Equine Vet J 2010; 42:274-81. [PMID: 20486986 DOI: 10.2746/042516409x479603] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Carbohydrate (CHO) stored in the form of skeletal muscle glycogen is the main energy source for glycolytic and oxidative ATP production during vigorous exercise in mammals. In man, horse and dog both short-term high intensity and prolonged submaximal exercise deplete muscle glycogen. In horses, however, muscle glycogen synthesis is 2-3-fold slower than in man and rat, even when a diet high in soluble CHO is fed. There appear to be significant differences in CHO and glycogen metabolism between horses and other mammals, and it is becoming increasingly clear that many conclusions drawn from human exercise physiology do not apply to horses. This review aims to provide a comprehensive, comparative summary of the research on muscle glycogen synthesis in horse, man and rodent. Species differences in CHO uptake and utilisation are examined and the issues with feeding high soluble CHO diets to horses are discussed. Alternative feeding strategies, including protein and long and short chain fatty acid supplementation and the importance of rehydration, are explored.
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Affiliation(s)
- A P Waller
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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Lacombe VA, Hinchcliff KW, Kohn CW, Reed SM, Taylor LE. Effects of dietary glycaemic response after exercise on blood concentrations of substrates used indirectly for muscle glycogenesis. Equine Vet J 2010:585-9. [PMID: 17402488 DOI: 10.1111/j.2042-3306.2006.tb05609.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
REASONS FOR PERFORMING STUDY Exercise depletes muscle glycogen stores, which could subsequently impair performance. Muscle glycogen replenishment is determined by substrate availability. OBJECTIVES To study the effects of feeding meals of varying glycaemic responses on blood concentrations of substrates used for glycogenesis in horses with exercise-induced glycogen depletion. METHODS In a 3-way crossover study, 7 horses received each of 3 isocaloric diets for 72 h after undergoing glycogen-depleting exercise: 1) a high soluble-carbohydrate diet, which induced a high-glycaemic (HGI) response; 2 and 3) a low soluble-carbohydrate or a mixed soluble-carbohydrate diet (control group), which both induced a similar low-to-moderate glycaemic (LGI) response. Muscle biopsies and venous samples were collected before and up to 72 h after exercise. RESULTS Feeding HGI diet resulted in a higher (P<0.001) rate of muscle glycogenesis over 72 h compared to LGI diets. Plasma glycerol, triglyceride, lactate, serum NEFA and total protein concentrations, and haematocrit were significantly (P<0.001) higher after compared to before exercise. Whereas no significant overall dietary effect was observed on these metabolites over 72 h, there was a tendency for glycerol, NEFA and triglyceride concentrations to be lower for LGI compared to HGI diets over 6 h after exercise (P<0.05; 1, 6 and 4-6 h after exercise, respectively). CONCLUSIONS These data suggest that horses fed LGI meals after exercise had limited lipid utilisation without any significant shift of substrate utilisation toward gluconeogenesis, which could have contributed to the slower rate of muscle glycogenesis compared to horses fed HGI diets.
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Affiliation(s)
- V A Lacombe
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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Waller AP, Geor RJ, Spriet LL, Heigenhauser GJF, Lindinger MI. Oral acetate supplementation after prolonged moderate intensity exercise enhances early muscle glycogen resynthesis in horses. Exp Physiol 2009; 94:888-98. [PMID: 19429643 DOI: 10.1113/expphysiol.2009.047068] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Oral acetate supplementation enhances glycogen synthesis in some mammals. However, while acetate is a significant energy source for skeletal muscle at rest in horses, its effects on glycogen resynthesis are unknown. We hypothesized that administration of an oral sodium acetate-acetic acid solution with a typical grain and hay meal after glycogen-depleting exercise would result in a rapid appearance of acetate in blood with rapid uptake by skeletal muscle. It was further hypothesized that acetate taken up by muscle would be converted to acetyl CoA (and acetylcarnitine), which would be metabolized to CO2 and water via the tricarboxylic acid cycle, generating ATP within the mitochondria and thereby allowing glucose taken up by muscle to be preferentially incorporated into glycogen. Gluteus medius biopsies and jugular venous blood were sampled from nine exercise-conditioned horses on two separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of a 3 day event. After the CETs, horses were allowed water ad libitum and either 8 l of a hypertonic sodium acetate-acetic acid solution via nasogastric gavage followed by a typical hay-grain meal (acetate treatment) or a hay-grain meal alone (control treatment). The CET significantly decreased muscle glycogen concentration by 21 and 17% in the acetate and control treatments, respectively. Acetate supplementation resulted in a rapid and sustained increase in plasma [acetate]. Skeletal muscle [acetyl CoA] and [acetylcarnitine] were increased at 4 h of recovery in the acetate treatment, suggesting substantial tissue extraction of the supplemented acetate. Acetate supplementation also resulted in an enhanced rate of muscle glycogen resynthesis during the initial 4 h of the recovery period compared with the control treatment; however, by 24 h of recovery there was no difference in glycogen replenishment between trials. It is concluded that oral acetate could be an alternative energy source in the horse.
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Affiliation(s)
- Amanda P Waller
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada N1G2W1.
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Waller AP, Heigenhauser GJF, Geor RJ, Spriet LL, Lindinger MI. Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses. J Appl Physiol (1985) 2009; 106:91-100. [DOI: 10.1152/japplphysiol.90783.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrolyte solution (electrolyte) via nasogastric tube, followed by a typical hay/grain meal, or a hay/grain meal alone (control). The CET resulted in decreased total body water and muscle glycogen concentration of 8.4 ± 0.3 liters and 22.6%, respectively, in the control treatment, and 8.2 ± 0.4 liters and 21.9% in the electrolyte treatment. Electrolyte resulted in an enhanced rate of muscle glycogen resynthesis and faster restoration of hydration (as evidenced by faster recovery of plasma protein concentration, maintenance of plasma osmolality, and greater muscle intracellular fluid volume) during the recovery period compared with control. There were no differences in muscle Na, K, Cl, or Mg contents between the two treatments. It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise enhanced the rate of muscle glycogen resynthesis during the recovery period compared with control. It is speculated that postexercise dehydration may be one key contributor to the slow muscle glycogen replenishment in horses.
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Abstract
AbstractAn optimally functional musculoskeletal system is crucial for athletic performance and even minor perturbations can limit athletic ability. The introduction of the muscle biopsy technique in the 1970s created a window of opportunity to examine the form and function of equine skeletal muscle. Muscle histochemical and biochemical analyses have allowed characterization of the properties of equine muscle fibres and their influence on, and adaptation to, physical exertion. Analyses of exercise responses during standardized treadmill exercise and field studies have illustrated the role of cellular energetics in determining athletic suitability for specific disciplines, mechanisms of fatigue, adaptations to training and the affect of diet on metabolic responses. This article provides a review of the tools available to study muscle energetics in the horse, discusses the muscular metabolic pathways and summarizes the energetics of exercise.
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Jose-Cunilleras E, Hinchcliff KW, Lacombe VA, Sams RA, Kohn CW, Taylor LE, Devor ST. Ingestion of starch-rich meals after exercise increases glucose kinetics but fails to enhance muscle glycogen replenishment in horses. Vet J 2006; 171:468-77. [PMID: 16624713 DOI: 10.1016/j.tvjl.2005.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2005] [Indexed: 11/25/2022]
Abstract
Fatiguing exercise substantially decreases muscle glycogen concentration in horses, impairing athletic performance in subsequent exercise bouts. Our objective was to determine the effect of ingestion of starch-rich meals after exercise on whole body glucose kinetics and muscle glycogen replenishment. In a randomized, cross-over study seven horses with exercise-induced muscle glycogen depletion were either not fed for 8 h, fed half of the daily energy requirements ( approximately 15 Mcal DE) as hay, or fed an isocaloric amount of corn 15 min and 4 h after exercise. Starch-rich meals fed after exercise, when compared to feed withholding, resulted in mild to moderate hyperglycemia (5.7+/-0.3 vs. 4.7+/-0.3 mM, P<0.01) and hyperinsulinemia (79.9+/-9.3 vs. 39.0+/-1.9 pM, P<0.001), 3-fold greater whole body glucose kinetics (15.5+/-1.4 vs. 5.3+/-0.4 micromol kg(-1)min(-1), P<0.05), but these only minimally enhanced muscle glycogen replenishment (171+/-19 vs. 170+/-56 and 260+/-45 vs. 294+/-29 mmol/kg dry weight immediately and 24 h after exercise, P>0.05). It is concluded that after substantial exercise-induced muscle glycogen depletion, feeding status only minimally affects net muscle glycogen concentrations after exercise, despite marked differences in soluble carbohydrate ingestion and availability of glucose to skeletal muscle.
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Affiliation(s)
- Eduard Jose-Cunilleras
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH 43210, USA.
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