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Heemstra LA, Koch LG, Britton SL, Novak CM. Altered skeletal muscle sarco-endoplasmic reticulum Ca 2+-ATPase calcium transport efficiency after a thermogenic stimulus. Am J Physiol Regul Integr Comp Physiol 2022; 323:R628-R637. [PMID: 36094445 PMCID: PMC9602703 DOI: 10.1152/ajpregu.00173.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/01/2022] [Accepted: 09/01/2022] [Indexed: 01/22/2023]
Abstract
Exposure to predator threat induces a rapid and robust increase in skeletal muscle thermogenesis in rats. The central nervous system relays threat information to skeletal muscle through activation of the sympathetic nervous system, but muscle mechanisms mediating this thermogenesis remain unidentified. Given the relevance of sarcolipin-mediated futile calcium cycling through the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) pump to mammalian muscle nonshivering thermogenesis, we hypothesized that this plays a role in contextually induced muscle thermogenesis as well. This was assessed by measuring enzymatic activity of SERCA and sarcoplasmic reticulum Ca2+ transport, where the apparent coupling ratio (Ca2+ uptake rate divided by ATPase activity rate at a standard Ca2+ concentration) was predicted to decrease in association with muscle thermogenesis. Sprague-Dawley rats exposed to predator (ferret) odor (PO) showed a rapid decrease in the apparent coupling ratio in the soleus muscle, indicating SERCA uncoupling compared with control-odor-exposed rats. A rat model of high aerobic fitness and elevated muscle thermogenesis also demonstrated soleus muscle SERCA uncoupling relative to their obesity-prone, low-fitness counterparts. Both the high- and low-aerobic fitness rats showed soleus SERCA uncoupling with exposure to PO. Finally, no increase in sarcolipin expression in soleus muscle was detected with PO exposure. This dataset implicates muscle uncoupling of SERCA Ca2+ transport and ATP hydrolysis, likely through altered SERCA or sarcolipin function outside of translational regulation, as one contributor to the muscle thermogenesis provoked by exposure to predator threat. These data support the involvement of SERCA uncoupling in both muscle thermogenic induction and enhanced aerobic capacity.
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Affiliation(s)
- Lydia A Heemstra
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Lauren G Koch
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Steven L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Colleen M Novak
- Department of Biological Sciences, Kent State University, Kent, Ohio
- School of Biomedical Sciences, Kent State University, Kent, Ohio
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2
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Jahn M, Seebacher F. Variations in cost of transport and their ecological consequences: a review. J Exp Biol 2022; 225:276242. [PMID: 35942859 DOI: 10.1242/jeb.243646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Movement is essential in the ecology of most animals, and it typically consumes a large proportion of individual energy budgets. Environmental conditions modulate the energetic cost of movement (cost of transport, COT), and there are pronounced differences in COT between individuals within species and across species. Differences in morphology affect COT, but the physiological mechanisms underlying variation in COT remain unresolved. Candidates include mitochondrial efficiency and the efficiency of muscle contraction-relaxation dynamics. Animals can offset increased COT behaviourally by adjusting movement rate and habitat selection. Here, we review the theory underlying COT and the impact of environmental changes on COT. Increasing temperatures, in particular, increase COT and its variability between individuals. Thermal acclimation and exercise can affect COT, but this is not consistent across taxa. Anthropogenic pollutants can increase COT, although few chemical pollutants have been investigated. Ecologically, COT may modify the allocation of energy to different fitness-related functions, and thereby influence fitness of individuals, and the dynamics of animal groups and communities. Future research should consider the effects of multiple stressors on COT, including a broader range of pollutants, the underlying mechanisms of COT and experimental quantifications of potential COT-induced allocation trade-offs.
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Affiliation(s)
- Miki Jahn
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
| | - Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
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3
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Roussel D, Le Coadic M, Rouanet JL, Duchamp C. Skeletal muscle metabolism in sea-acclimatized king penguins. I. Thermogenic mechanisms. J Exp Biol 2020; 223:jeb233668. [PMID: 32968000 DOI: 10.1242/jeb.233668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/10/2020] [Indexed: 12/25/2022]
Abstract
At fledging, king penguin juveniles undergo a major energetic challenge to overcome the intense and prolonged energy demands for thermoregulation and locomotion imposed by life in cold seas. Among other responses, sea acclimatization triggers fuel selection in skeletal muscle metabolism towards lipid oxidation in vitro, which is reflected by a drastic increase in lipid-induced thermogenesis in vivo However, the exact nature of skeletal muscle thermogenic mechanisms (shivering and/or non-shivering thermogenesis) remains undefined. The aim of the present study was to determine in vivo whether the capacity for non-shivering thermogenesis was enhanced by sea acclimatization. We measured body temperature, metabolic rate, heart rate and shivering activity in fully immersed king penguins (Aptenodytes patagonicus) exposed to water temperatures ranging from 12 to 29°C. Results from terrestrial pre-fledging juveniles were compared with those from sea-acclimatized immature penguins (hereafter 'immatures'). The capacity for thermogenesis in water was as effective in juveniles as in immatures, while the capacity for non-shivering thermogenesis was not reinforced by sea acclimatization. This result suggests that king penguins mainly rely on skeletal muscle contraction (shivering or locomotor activity) to maintain endothermy at sea. Sea-acclimatized immature penguins also exhibited higher shivering efficiency and oxygen pulse (amount of oxygen consumed or energy expended per heartbeat) than pre-fledging juvenile birds. Such increase in shivering and cardiovascular efficiency may favor a more efficient activity-thermoregulatory heat substitution providing penguins with the aptitude to survive the tremendous energetic challenge imposed by marine life in cold circumpolar oceans.
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Affiliation(s)
- Damien Roussel
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Marion Le Coadic
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Jean-Louis Rouanet
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Claude Duchamp
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
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4
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Roussel D, Marmillot V, Monternier PA, Bourguignon A, Toullec G, Romestaing C, Duchamp C. Skeletal muscle metabolism in sea-acclimatized king penguins. II. Improved efficiency of mitochondrial bioenergetics. J Exp Biol 2020; 223:jeb233684. [PMID: 32967994 DOI: 10.1242/jeb.233684] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/10/2020] [Indexed: 08/25/2023]
Abstract
At fledging, juvenile king penguins (Aptenodytes patagonicus) must overcome the tremendous energetic constraints imposed by their marine habitat, including during sustained extensive swimming activity and deep dives in cold seawater. Both endurance swimming and skeletal muscle thermogenesis require high mitochondrial respiratory capacity while the submerged part of dive cycles repeatedly and greatly reduces oxygen availability, imposing a need for solutions to conserve oxygen. The aim of the present study was to determine in vitro whether skeletal muscle mitochondria become more 'thermogenic' to sustain heat production or more 'economical' to conserve oxygen in sea-acclimatized immature penguins (hereafter 'immatures') compared with terrestrial juveniles. Rates of mitochondrial oxidative phosphorylation were measured in permeabilized fibers and mitochondria from the pectoralis muscle. Mitochondrial ATP synthesis and coupling efficiency were measured in isolated muscle mitochondria. The mitochondrial activities of respiratory chain complexes and citrate synthase were also assessed. The results showed that respiration, ATP synthesis and respiratory chain complex activities in pectoralis muscles were increased by sea acclimatization. Furthermore, muscle mitochondria were on average 30-45% more energy efficient in sea-acclimatized immatures than in pre-fledging juveniles, depending on the respiratory substrate used (pyruvate, palmitoylcarnitine). Hence sea acclimatization favors the development of economical management of oxygen, decreasing the oxygen needed to produce a given amount of ATP. This mitochondrial phenotype may improve dive performance during the early marine life of king penguins, by extending their aerobic dive limit.
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Affiliation(s)
- Damien Roussel
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Vincent Marmillot
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Pierre-Axel Monternier
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Aurore Bourguignon
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Gaëlle Toullec
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Caroline Romestaing
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Claude Duchamp
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
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5
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Gorrell E, Shemery A, Kowalski J, Bodziony M, Mavundza N, Titus AR, Yoder M, Mull S, Heemstra LA, Wagner JG, Gibson M, Carey O, Daniel D, Harvey N, Zendlo M, Rich M, Everett S, Gavini CK, Almundarij TI, Lorton D, Novak CM. Skeletal muscle thermogenesis induction by exposure to predator odor. J Exp Biol 2020; 223:jeb218479. [PMID: 32165434 PMCID: PMC7174837 DOI: 10.1242/jeb.218479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/02/2020] [Indexed: 01/07/2023]
Abstract
Non-shivering thermogenesis can promote negative energy balance and weight loss. In this study, we identified a contextual stimulus that induces rapid and robust thermogenesis in skeletal muscle. Rats exposed to the odor of a natural predator (ferret) showed elevated skeletal muscle temperatures detectable as quickly as 2 min after exposure, reaching maximum thermogenesis of >1.5°C at 10-15 min. Mice exhibited a similar thermogenic response to the same odor. Ferret odor induced a significantly larger and qualitatively different response from that of novel or aversive odors, fox odor or moderate restraint stress. Exposure to predator odor increased energy expenditure, and both the thermogenic and energetic effects persisted when physical activity levels were controlled. Predator odor-induced muscle thermogenesis is subject to associative learning as exposure to a conditioned stimulus provoked a rise in muscle temperature in the absence of the odor. The ability of predator odor to induce thermogenesis is predominantly controlled by sympathetic nervous system activation of β-adrenergic receptors, as unilateral sympathetic lumbar denervation and a peripherally acting β-adrenergic antagonist significantly inhibited predator odor-induced muscle thermogenesis. The potential survival value of predator odor-induced changes in muscle physiology is reflected in an enhanced resistance to running fatigue. Lastly, predator odor-induced muscle thermogenesis imparts a meaningful impact on energy expenditure as daily predator odor exposure significantly enhanced weight loss with mild calorie restriction. This evidence signifies contextually provoked, centrally mediated muscle thermogenesis that meaningfully impacts energy balance.
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Affiliation(s)
- Erin Gorrell
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Ashley Shemery
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Jesse Kowalski
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Miranda Bodziony
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Nhlalala Mavundza
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Amber R Titus
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Mark Yoder
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Sarah Mull
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Lydia A Heemstra
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Jacob G Wagner
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Megan Gibson
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Olivia Carey
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Diamond Daniel
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Nicholas Harvey
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Meredith Zendlo
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Megan Rich
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Scott Everett
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Chaitanya K Gavini
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Tariq I Almundarij
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, PO Box 6622, Buraidah 51452, Saudi Arabia
| | - Diane Lorton
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Colleen M Novak
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
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Zhang Y, Carter T, Eyster K, Swanson DL. Acute cold and exercise training up-regulate similar aspects of fatty acid transport and catabolism in house sparrows (Passer domesticus). ACTA ACUST UNITED AC 2015; 218:3885-93. [PMID: 26486368 DOI: 10.1242/jeb.126128] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 10/08/2015] [Indexed: 12/21/2022]
Abstract
Summit maximum thermoregulatory metabolic rate (Msum) and maximum exercise metabolic rate (MMR) both increase in response to acute cold or exercise training in birds. Because lipids are the main fuel supporting both thermogenesis and exercise in birds, adjustments to lipid transport and catabolic capacities may support elevated energy demands from cold and exercise training. To examine a potential mechanistic role for lipid transport and catabolism in organismal cross-training effects (exercise effects on both exercise and thermogenesis, and vice versa), we measured enzyme activities and mRNA and protein expression in pectoralis muscle for several key steps of lipid transport and catabolism pathways in house sparrows (Passer domesticus) during acute exercise and cold training. Both training protocols elevated pectoralis protein levels of fatty acid translocase (FAT/CD36), cytosolic fatty acid-binding protein, and citrate synthase (CS) activity. However, mRNA expression of FAT/CD36 and both mRNA and protein expression of plasma membrane fatty acid-binding protein did not change for either training group. CS activities in supracoracoideus, leg and heart, and carnitine palmitoyl transferase (CPT) and β-hydroxyacyl CoA-dehydrogenase activities in all muscles did not vary significantly with either training protocol. Both Msum and MMR were significantly positively correlated with CPT and CS activities. These data suggest that up-regulation of trans-sarcolemmal and intramyocyte lipid transport capacities and cellular metabolic intensities, along with previously documented increases in body and pectoralis muscle masses and pectoralis myostatin (a muscle growth inhibitor) levels, are common mechanisms underlying the training effects of both exercise and shivering in birds.
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Affiliation(s)
- Yufeng Zhang
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - Travis Carter
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - Kathleen Eyster
- Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57105, USA
| | - David L Swanson
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
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7
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Zhang Y, Eyster K, Liu JS, Swanson DL. Cross-training in birds: cold and exercise training produce similar changes in maximal metabolic output, muscle masses and myostatin expression in house sparrows (Passer domesticus). ACTA ACUST UNITED AC 2015; 218:2190-200. [PMID: 25987736 DOI: 10.1242/jeb.121822] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/08/2015] [Indexed: 01/18/2023]
Abstract
Maximal metabolic outputs for exercise and thermogenesis in birds presumably influence fitness through effects on flight and shivering performance. Because both summit (Msum, maximum thermoregulatory metabolic rate) and maximum (MMR, maximum exercise metabolic rate) metabolic rates are functions of skeletal muscle activity, correlations between these measurements and their mechanistic underpinnings might occur. To examine whether such correlations occur, we measured the effects of experimental cold and exercise training protocols for 3 weeks on body (Mb) and muscle (Mpec) masses, basal metabolic rate (BMR), Msum, MMR, pectoralis mRNA and protein expression for myostatin, and mRNA expression of TLL-1 and TLL-2 (metalloproteinase activators of myostatin) in house sparrows (Passer domesticus). Both training protocols increased Msum, MMR, Mb and Mpec, but BMR increased with cold training and decreased with exercise training. No significant differences occurred for pectoralis myostatin mRNA expression, but cold and exercise increased the expression of TLL-1 and TLL-2. Pectoralis myostatin protein levels were generally reduced for both training groups. These data clearly demonstrate cross-training effects of cold and exercise in birds, and are consistent with a role for myostatin in increasing pectoralis muscle mass and driving organismal increases in metabolic capacities.
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Affiliation(s)
- Yufeng Zhang
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - Kathleen Eyster
- Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57105, USA
| | - Jin-Song Liu
- School of Life and Environmental Sciences, Wenzhou University, Wenzhou 325035, China
| | - David L Swanson
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
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Mineo PM, Cassell EA, Roberts ME, Schaeffer PJ. Chronic cold acclimation increases thermogenic capacity, non-shivering thermogenesis and muscle citrate synthase activity in both wild-type and brown adipose tissue deficient mice. Comp Biochem Physiol A Mol Integr Physiol 2011; 161:395-400. [PMID: 22233932 DOI: 10.1016/j.cbpa.2011.12.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 10/31/2011] [Accepted: 12/20/2011] [Indexed: 10/14/2022]
Abstract
The purpose of this study was to determine whether chronic cold exposure would increase the aerobic capacity of skeletal muscle in UCP-dta mice, a transgenic line lacking brown adipose tissue (BAT). Wild type and UCP-dta mice were acclimated to either warm (23 °C), or cold (4 °C) conditions. Cold increased muscle oxidative capacity nearly equivalently in wild-type and UCP-dta mice, but did not affect the respiratory function of isolated mitochondria. Summit metabolism ( ̇V O2summit) and norepinephrine-induced thermogenesis ( ̇V O2NST) were significantly lower in UCP-dta mice relative to wild-type mice regardless of temperature treatment, but both were significantly higher in cold relative to warm acclimated mice. BAT mass was significantly higher in the cold relative to warm acclimated wild-type mice, but not in cold acclimated UCP-dta mice. BAT citrate synthase activity was lower in transgenic animals regardless of acclimation temperature and BAT citrate synthase activity per depot was significantly higher only in the cold acclimated wild-type mice. Muscle citrate synthase activity was increased in both genotypes. As defects in muscle oxidative function have been observed with obesity and type 2 diabetes, these results suggest that chronic cold exposure is a useful intervention to drive skeletal muscle oxidative capacity in mouse models of obesity.
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Affiliation(s)
- P M Mineo
- Department of Zoology, Miami University, Oxford, OH 45056, USA
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Ohmura H, Hiraga A, Matsui A, Aida H, Inoue Y, Asai Y, Jones JH. Physiological responses of young Thoroughbreds during their first year of race training. Equine Vet J 2002:140-6. [PMID: 12405675 DOI: 10.1111/j.2042-3306.2002.tb05407.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Yearling horses are typically trained for more than a year before they begin racing; therefore, we questioned how relevant analyses of the initial responses to training are compared to physiological responses that occur over a year of training, and whether young horses with no history of training would respond the same as older horses that had been trained previously. We hypothesised that changes in O2 transport over the last months of a year of training would be different than at the beginning. We trained 5 yearling Thoroughbreds and evaluated metabolism, O2 transport and echocardiograms. Measurements were made before breaking (T1), after 6 months of training (T2) and following an additional 4 months of training (T3). We compared 5 trained horses (TR) with 5 untrained (UT) sex-, size- and age-matched yearlings kept at pasture and in boxes. Satellite telemetry indicated UT moved less total daily distance than TR during winter and more during summer, but UT walked for 80% of their distance, TR only 25%. The UT increased body mass (Mb) after T1 by 13% and were significantly heavier and fatter than TR. Specific aerobic capacity (VO2max/Mb) increased by 16% in both groups at T2, but by T3 was not different from T1 in UT, but was higher in TR (19%>T1, 15%>UT). In TR, specific cardiac output (Q/Mb) increased by 13% at T2, and specific stroke volume (V(S)/Mb) were larger at T2 and T3 than T1 and UT at the same times both by physiological (15-16%) and echocardiographical (22-23%) estimates. Increased Vs was a primary correlate of the sustained increase in VO2max/Mb in TR. The large increases in V(S) and VO2max had occurred by T2 and changed only slightly by T3.
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Affiliation(s)
- H Ohmura
- Equine Science Division, Hidaka Training and Research Center, Japan Racing Association, Urakawa-gun, Hokkaido
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10
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Affiliation(s)
- Jurgen Schnermann
- National Institute of Diabetes and Digestive and Kidney Diseases/NIH, Bethesda, MD 20892, USA.
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