bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma β‐endorphin, cortisol and immune responses to acute exercise are altered by age and exercise training in horses
Authors: MALINOWSKI K. , SHOCK E. J. , ROCHELLE P. , KEARNS C. F. , GUIRNALDA P. D. , McKEEVER K. H. 
Published: June 2010

SummaryReasons for performing study:Ageing appears to affect immune and neuroendocirne function in horses and response to acute exercise. No studies have examined the combined effects of training and ageing on immune and neuroendocirne function in horses.Hypothesis:To ascertain whether training and age would affect the plasma β‐endorphin (BE) and cortisol (C) as well as immune function responses to acute exercise in Standardbred mares.Methods:Graded exercise tests (GXT) and simulated race tests (SRT) were performed before and after 12 weeks training at 60% HRmax. BE and C were measured at rest and at 5, 10, 20, 40, 60 and 120 min post GXT. Leucocyte cell number, CD4+and CD8+lymphocyte subsets, and mitogen stimulated lymphoproliferative response (LPR), were measured in jugular blood before and after the SRTs.Results:Cortisol rose by 5 min post GXT in young (Y) and middle‐age (MA) mares (P<0.05) and remained elevated until 40 and 60 min post GXT, respectively during both pre‐ and post training GXT. There was no rise in C in old (O) mares after either GXT (P>0.05). Pretraining BE rose (P<0.05) by 5 min post GXT in all mares. After training, BE was higher in Y and O vs. MA (P<0.05) at 5 min post GXT. Post training BE was higher at 5 min post GXT in Y and O vs. pretraining (P<0.05). After SRT, lymphocyte number rose in all mares (P<0.05); however, lower lymphocyte numbers (P<0.05) were seen in MA vs. Y and O vs. MA (P<0.05). The O had reduced LPR to Con A and PHA stimulation (P<0.05) compared to Y and MA after the SRT after both pre‐ and post training SRT. LPR to PWM was lower (P<0.05) in O vs. Y and MA after the pretraining SRT. Training caused an increase in resting LPR to PWM in MA only (P<0.05).Conclusion:Both age and training altered the plasma β‐endorphin and cortisol responses as well as and immune responses to acute exercise.Potential relevance:This study provides important information on the effects of ageing and training that will aid in the management and care of an increasing number of active older horses.
The effects of dietary N‐3 and antioxidant supplementation on erythrocyte membrane fatty acid composition and fluidity in exercising horses
Authors: PORTIER K. , de MOFFARTS B. , FELLMAN N. , KIRSCHVINK N. , MOTTA C. , LETELLIER C. , RUELLAND A. , Van ERCK E. , LEKEUX P. , COUDERT J. 
Published: June 2010

SummaryReasons for performing study:Fatty acid supplementation could modulate erythrocyte membrane fluidity in horses at rest and during exercise, but information is lacking on the effect of exercise.Objectives:To assess the effect of exercise with, and without, an oral antioxidant supplementation enriched with n‐3 fatty acids on erythrocyte membrane fluidity (EMF) and fatty acid composition in eventing horses.Methods:Twelve healthy and regularly trained horses were divided randomly into 2 groups:group Sreceived an oral antioxidant cocktail enriched in n‐3 fatty acid (alphatocopherol, eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) whereasgroup Pwas placebo‐treated. At the end of 4 weeks, all horses performed a standardised exercise test (ET) under field conditions. Venous blood was sampled before starting treatment (T0), immediately before (T1) as well as 15 min (T2) and 24 h (T3) after ET. Spin labelled (16‐DOXYL‐stearic acid) red blood cell membranes were characterised using the relaxation correlation time (Tc in inverse proportion to EMF). Fatty acid composition (%) of the membrane was determined by gas‐liquid chromatography.Results:Supplementation did not induce changes in EMF (T1 vs. T0) but significant changes in membrane composition were observed and there were increases in n‐3 polyunsaturated fatty acid PUFA, n‐3/n‐6 ratio, and total n‐3 fatty acids. Exercise (T2 vs. T1) induced a significant decrease of EMF ingroup P(Tc: +19%, P<0.05) and nonsignificant decrease ingroup S(Tc: +5%), whereas membrane fatty acid composition did not change in either group. During the recovery period (T3 vs. T2), EMF decreased significantly ingroup S(Tc: +29%, P<0.05) and nonsignificantly ingroup P(Tc: +18%) without any significant changes in fatty acid composition.Conclusion and potential relevance:An enriched oral antioxidant supplementation induced changes in membrane composition, which modulated the decrease in EMF induced by exercise. Long chain n‐3 fatty acid supplementation might therefore be beneficial.
Hydration of exercised Standardbred racehorses assessed noninvasively using multi‐frequency bioelectrical impedance analysis
Authors: WALLER A. , LINDINGER M. I. 
Published: June 2010

SummaryReasons for performing study:In human and animal clinical practice, multi‐frequency bioelectrical impedance analysis (MF‐BIA) is increasingly used as a diagnostic tool to assess hydration of intra‐and extracellular fluid compartments. Accurate determination of changes in hydration status within individuals over time has remained problematic due to the requirement for complete impedance‐frequency relationships at the time points of interest.Objectives:To use MF‐BIA in 13 Standardbred racehorses and 7 ‘endurance’ research horses to determine if MF‐BIA could be used to track changes in total body water (TBW), intracellular fluid volume (ICFV) and extracellular fluid volume (ECFV) resulting from exercise.Methods:Jugular venous blood was sampled at rest and for 2–13 h following exercise. TBW, ECFV and plasma volume (PV) were measured at rest using indicator dilution techniques (D2O, thiocyanate and Evans Blue, respectively). TBW, ECFV, ICFV and PV were correlated to impedance measures and predictive equations used to determine hydration status from MF‐BIA measures.Results:TBW loss continued throughout the recovery period, and was primarily borne by the ECF compartment at 90 min of recovery.Conclusions:MF‐BIA predictions of compartmental hydration status were significantly correlated to measured/calculated decreases in these compartments.Potential relevance:Practical applications for MF‐BIA in horses include monitoring of hydration status during transport and competition, assessment of body compostion, clinical health assessment and critical care management.
Is improved high speed performance following frusemide administration due to diuresis‐induced weight loss or reduced severity of exercise‐induced pulmonary haemorrhage?
Authors: ZAWADZKAS X. A. , SIDES R. H. , BAYLY W. M. 
Published: June 2010

SummaryReasons for performing study:Prerace administration of frusemide to horses has been linked with a significant improvement in racing performance, but the basis for this improvement is unclear.Objective:To test whether improved performance with prerace administration of frusemide is due to the drug's diuresis‐induced weight loss rather than its apparent alleviation of exercise‐induced pulmonary haemorrhage (EIPH).Methods:Eight thoroughbred horses underwent 3 trials in a random order, 2 or 3 weeks apart: control (C), frusemide/unburdened (FU), and frusemide/burdened (FB). None of the horses were known to have exhibited post‐exercise epistaxis or endoscopic evidence of EIPH. Endoscope‐guided bronchoalveolar lavages (BALs) were performed before and after each horse completed a standardised exercise test (SET) on an inclined treadmill to assess semi‐quantitatively the volume of EIPH. For C, horses received an i.v. saline placebo injection (5 ml) and were unburdened while performing the SET. With FU, horses received frusemide (0.5 mg/kg) and were also unburdened. For FB, horses received frusemide and were burdened with weight equal to that lost during the 4 h post frusemide injection period. Erythrocyte number in BAL fluid, mass specific VO2max, time and distance for the entire SET as well as at maximum speed were recorded. A one‐way repeated measures analysis of variance was conducted on all results.Results:Mass specific VO2maxwas significantly higher for the FU than for FB or C. Mass specific VO2maxfor FB and C were not different. More RBCs were found in BAL samples after C runs than after both FU and FB trial runs. Horses with the frusemide treatment (either burdened or unburdened) produced less EIPH than in the C trial, but their mass specific VO2maxvalues were higher on the FU trial alone. For FU, horses ran longer at 115% VO2maxthan under C or FB conditions.Conclusion and potential relevance:Improvement of performance in the furosemide trials was due more to the weight‐loss related effects of the drug than its apparent alleviation of EIPH. Further research is warranted with the same or similar project design, but with a larger sample size and with horses known to have more severe EIPH.
Effects of a pre‐moistened multilayered breathable fabric in promoting heat loss during recovery after exercise under hot conditions
Authors: FOREMAN J. H. , BENSON G. J. , FOREMAN M. H. 
Published: June 2010

SummaryReasons for performing study: Horses generate considerable internal heat burdens when exercising. Although common practice for a trainer or groom to place a wet blanket or towel on the dorsum of a hot horse post exercise, there are no data supporting the efficacy of this cooling method.Objective: To test the hypothesis that a pre‐moistened blanket designed with a multilayered breathable fabric would enhance heat loss in horses post exercise.Methods: Eight treadmill‐trained horses performed a standardised exercise test (SET) weekly for 3 weeks, with 3 different recovery treatments administered randomly. Pulmonary artery temperature (PAT) was measured via Swan‐Ganz catheter. The SET consisted of 10 min at 3.7 m/sec, 3 min at 11.0 m/sec, 25 min at 3.7 m/sec and 20 min of recovery walking at 2.0 m/sec (58 min exercise and recovery under laboratory conditions of 35.0–40.6°C and 27–49% RH). From 3–7 min during recovery, the treadmill was stopped and horses randomly received either: (a) no bath (negative control); (b) a bath consisting of 32 1 of 1–4°C water split into 3–4 cycles of bilateral water application (positive control) followed by water removal (‘scraping’); or (c) application of a multilayered fabric blanket soaked in 16–19°C water, wrung out, and placed over the dorsum and sides of the horse. PAT was compared using RM ANOVA with the Student Neuman‐Keul's test usedpost hocto discriminate between treatments at specific points in time.Results: Mean PAT rose with each phase of exercise (P<0.001) and peaked at a mean of 40.2 ± 0.2°C. During recovery, the cold bath decreased HR and PAT for 9 min after walking resumed (P<0.001‐P<0.05). The blanket did not decrease HR or PAT compared to negative control (P>0.05), and both were hotter than the cold bath treatment through 16 min of recovery (P<0.05).Conclusions: A specially‐designed cooling blanket failed to reduce PAT when compared to negative control. Cold water bathing decreased HR and PAT but was not effective throughout all of recovery.Potential relevance: A specially‐designed, pre‐moistened multilayered breathable fabric failed to promote evaporative cooling compared to negative control. Cold water baths may need to be repeated throughout recovery to optimise their effect.
Contribution of exercise intensity and duration to training‐linked myosin transitions in Thoroughbreds
Authors: RIVERO J. L. , RUZ A. , MARTI‐KORFF S. , LINDNER A. 
Published: June 2010

SummaryReasons for performing study: The influence of relevant exercise parameters such as intensity and duration of exercise on the muscular response to training has not been reported in Thoroughbreds. This knowledge may be of great value in practice.Objective: To define the relative contribution of the intensity and duration of exercise on the myosin heavy chain (MHC) response to training in Thoroughbred racehorses.Methods: Six 2–3‐year‐old Thoroughbreds, following a randomised 6 times 6 latin square design, performed 6 consecutive conditioning programmes of varying lactate‐guided intensities and durations. Each programme lasted 22 days and consisted of 11 exercise sessions once a day, every second day on a 6% inclined treadmill followed by a 10 day resting period between consecutive programmes. Gluteus muscle biopsies (depth, 2 and 6 cm) were taken before, and after, each programme and electrophoretically analysed for MHCs.Results: Overall, training increased the fraction of MHC HA (mean ± s.d., 41.1 ± 3.5% to 43.4 ± 4.42% P<0.001) and decreased that of MHC IIX isoform (from 50.2 ± 4.4% to 47.4 ± 5.6% P<0.001). Exercise intensity fixed effects on fast MHCs were highly significant (P<0.01), whereas exercise duration only had a marginal effect (P<0.1) on the IIA:IIX MHC ratio. On a per‐individual basis, training impact on fast MHCs was only significant (P<0.05) in horses exercised for the longest duration at both intensities.Conclusion: The short‐term training‐induced up‐regulation of MHC IIA and down‐regulation of MHC IIX in Thoroughbreds are more dependent on intensity than duration of exercise. However, protocols with exercises of moderate intensity and long duration can induce MHC changes similar to those promoted by programmes with exercises of higher intensities.Potential relevance: Exercises for up to 25 min/day at velocities eliciting a blood lactate concentration between 2.5 and 4 mmol/1 every second day for 3 weeks improve stamina in Thoroughbreds.
MCT1 and CD147 gene polymorphisms in Standardbred horses
Authors: REEBEN M. , KOHO N. M. , RAEKALLIO M. , HYYPPÄ S. , PÖSÖ A. R. 
Published: June 2010

SummaryReasons for performing study:Transport of lactate across membranes is facilitated by proton‐monocarboxylate transporters (MCT). The most widely distributed isoform is MCT1, which needs an ancillary protein CD147. Studies on erythrocytes have shown that high activity of MCT1 is inherited as the dominant allele and that activity is regulated through CD147. Mutations of human MCT1 have been described that appear to impair lactate transport in muscles and cause exertional rhabdomyolysis. There are no reports of this potential relationship in the horse.Objectives:To obtain sequences of equine MCT1 and CD147 to examine differences between horses with high and low lactate transport activity in their erythrocytes.Methods:Muscle biopsy samples were taken from 3 healthy Standardbred horses and from 7 horses which according to the owners had signs of myopathy after intense exercise. DNA and RNA were isolated and PCR analysis and sequencing performed.Results:Currently, PCR fragments covering 100% of MCT1 and 70% of CD147 coding region are retained and sequence analysis has demonstrated one single nucleotide polymorphism (SNP) in the C‐terminal area of MCT1 and one SNP in the extracellular domain of CD147. Both cause an amino acid change. The SNPs found are not related to lactate transport activity in erythrocytes or signs of myopathy.Conclusions:More samples need to be analysed to make conclusions on the significance of the polymorphisms found. Furthermore, full sequence coverage of the coding region of CD147 is needed.Potential relevance:The molecular probes produced could be used as tools to study gene regulation of lactate transport.
Effects of prior exercise on components of insulin signalling in equine skeletal muscle
Authors: McCUTCHEON L. J. , GEOR R. J. , PRATT S. E. , MARTINEAU E. , HO K. 
Published: June 2010

SummaryReasons for performing study:Exercise is an important stimulus for the regulation of numerous metabolic functions in muscle, but there has been little investigation of the mechanism of exercise‐enhanced glucose utilisation.Objective:To examine the effects of exercise on the signalling components Akt and glycogen synthase kinase‐3 (GSK3) involved in insulin regulation of glycogen synthase (GS) activity. It was hypothesised that hyperinsulinaemia and prior exercise would alter the extent of Akt phosphorylation and GSK3β deactivation and increase insulin stimulation of GS activity in skeletal muscle.Methods:Eight Standardbred horses completed a euglycaemic‐hyperinsulinaemic clamp (EHC) either without prior exercise (NonEX) or at 0.5, 4 or 24 h post exercise (0.5 PostEX, 4 PostEX, and 24 PostEX, respectively). Muscle samples for determination of Akt and GSK3 serine phosphorylation, and GS fractional velocity (GSFV) were collected 5 min before (Pre‐INS) and at the end (Post‐INS) of each EHC (pre‐ and post insulin stimulation). Protein was separated by SDS‐PAGE on polyacrylamide gels, transferred to nitrocellulose membranes and incubated with antibodies against phospho‐Akt Ser473and GSK3α/β Ser21/9.Results:GSFVwas increased (P<0.05) 2‐fold at 0.5 PostEX, 4 PostEX and 24 PostEX when compared to NonEX in Pre‐INS and in Post‐INS was increased 33 and 28% in NonEX and at 24PostEX (P<0.05), respectively, when compared to Pre‐INS in these trials. Phospho‐Akt Ser473was increased at 0.5 PostEX only (P<0.05) in Pre‐INS but increased in all trials in Post‐INS. Phospho‐GSK3α (Ser21) was also greater (P<0.05) at 0.5 PostEX in Pre‐INS than in NonEX and 24 PostEX and in Post‐INS increased (P<0.05) in NonEX and at 24 PostEX but not at 0.5 PostEX or 4 PostEX post exercise. There was no effect of time or treatment on GSK3, (Ser9) phosphorylation or on total GSK3.Conclusions:Elevated plasma insulin and prior exercise were associated with Akt activation and GSK3α deactivation (0.5 PostEX) indicating that an effect of exercise is evident in the early post exercise period and supporting a physiological role for GSK3α in the regulation of GS activity. The changes are consistent with insulin signalling downstream from these molecules.
Monocarboxylate transporters (MCT) as lactate carriers in equine muscle and red blood cells
Authors: KOHO N. M. , HYYPPÄ S. , PÖSÖ A. R. 
Published: June 2010

SummaryReasons for performing study: Monocarboxylate transporters (MCT) facilitate the transport of lactate across membranes. In red blood cells (RBC) the transport activity varies interindividually due to differences in the amount of an ancillary protein CD147. Similar variations in muscles could have a great influence on lactate accumulation during exercise.Objectives: To study the expression of MCT isoforms and CD147 in the middle gluteal muscle.Methods: Venous blood and muscle biopsy samples were taken from 14 Standardbred horses. Lactate transport activity in RBC and the amounts of MCT1, 2, 4 and CD147 were measured.Results: In muscle MCT1, MCT4 and CD147 were found. Amount of MCT1 was variable and not dependent on age or training. Expression of MCT4 increased with age and correlated positively with CD147. CD147 in muscle correlated with that in RBC. MCT4 in muscle and CD147/MCT1 in RBC were higher in race fit than in moderately trained horses.Conclusions: MCT isoform profile in equine muscle is similar to that in man. The correlation between CD147 in muscle and RBC supports the view that lactate transport activity in muscles may vary interindividually as with RBC.Potential relevance: A larger number of horses need to be analysed to confirm the relationship of CD147 in muscle and RBC; and to allow the use the lactate transport activity in RBC as an indicator of the respective activity in muscles.
Gene expression profiling in equine muscle tissues using mouse cDNA microarrays
Authors: MUCHER E. , JAYR L. , ROSSIGNOL F. , AMIOT F. , GIDROL X. , BARREY E. 
Published: June 2010

SummaryReasons for performing study:Progress could be achieved by using microarrays to understand metabolic adaptations and disorders in equine muscle in response to exercise.Objectives:To test the feasibility of using mouse cDNA microarrays to analyse gene expression profile in normal equine muscles.Methods:Muscular biopsies of dorsalgluteus mediusandlongissimus lumborumwere done in 4 healthy Standardbreds. Total RNA was extracted from the muscle samples. The concentration and quality of RNA were measured before and after amplification. Gene expression profiles were measured using mouse cDNA microarrays including 15,264 unique genes representing about 11,000 documented genes. Three hybridisation tests were performed to check interspecificity, reproducibility and to compare gene expression in these muscles. For each test, a dye‐swap hybridisation with Cy3 and Cy5 fluoromarkers were done and the gene list filtered according the signal level.Results:According to the specificity test, the mouse cDNA microarrays were correctly hybridised by equine muscle cDNA. All positive control genes (GAPDH, HPRT and beta‐Actin) and no negative control gene (yeast, plant) hybridised. The reproducibility test demonstrated a good linearity between the duplicate hybridisations: 99.99% of the significant expressed genes have an expression ratio between 1.4 and 1/1.4 = 0.71. These limits can be considered as the thresholds to qualify as up‐regulated (ratio >1.4) or down‐regulated (ratio <0.71). In the muscle comparison test betweengluteus mediusvs.longissimus lumborum, 63 genes were found up‐regulated and 8 genes down‐regulated. The range of gene expression ratios in thegluteus mediuswas 0.61‐8.31 x thelongissimus lumborum.This list of modulated genes was classified by functions using a gene ontology data basis.Conclusion:Mouse microarrays could be used to hybridise equine RNA extracted from muscle tissues. For many genes there are large sequence identities that allowed interspecific cDNA hybridisation. The sensitivity of the method allowed quantification of up‐ and down‐regulated genes after applying appropriate filters.Potential relevance:Expression profiling could be used to explore the muscle metabolism changes related to exercise, training, pathology and illegal medication in horses.
Effects of egg‐bar shoes on the 3‐dimensional kinematics of the distal forelimb in horses walking on a sand track
Authors: CHATEAU H. , DEGUEURCE C. , DENOIX J. ‐M. 
Published: June 2010

SummaryReasons for performing study:Understanding of the biomechanical effects of egg‐bar shoes remains incomplete because kinematic studies are usually performed on hard tracks and with skin markers that do not measure the actual 3‐dimensional (3D) movements of the 3 digital joints.Objective:To quantify the effects of egg‐bar shoes on the 3D kinematics of the distal forelimb in horses walking on a sand track.Methods:Four healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while the horses were walking on a sand track. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with egg‐bar shoes were compared to those obtained with standard shoes. Mean differences were expressed in a 0.95 confidence interval.Results:With egg‐bar shoes, the initial sinking of the heels into the ground during landing was reduced and the heels were raised by up to 5.1° (3.5–6.7°) compared to standard shoes at mid‐stance. Concurrently, maximal flexion of the distal (DIPJ) and proximal (PIPJ) interphalangeal joints was increased by up to 3.2° (2.2–4.2°) and 1.8° (1.1–2.5°), respectively, at the beginning of the stance phase. At heel‐off, extension of the DIPJ was reduced by 3.8° (2.6–5.0°). In extrasagittal planes of movement, egg‐bar shoes prevented sinking of the medial quarter into the ground which led to a slight decrease of DIPJ medial rotation and lateromotion.Conclusions:Egg‐bar shoes prevent the heels and, to a lesser extent, the medial side of the hoof from sinking into the ground on a sand track. They contribute to a decrease of DIPJ maximal extension at heel‐off and to hoof stabilisation in the transversal plane.Potential relevance:Such quantitative results support the clinical indications of egg‐bar shoes.