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Poole DC, Copp SW, Colburn TD, Craig JC, Allen DL, Sturek M, O'Leary DS, Zucker IH, Musch TI. Guidelines for animal exercise and training protocols for cardiovascular studies. Am J Physiol Heart Circ Physiol 2020; 318:H1100-H1138. [PMID: 32196357 DOI: 10.1152/ajpheart.00697.2019] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Whole body exercise tolerance is the consummate example of integrative physiological function among the metabolic, neuromuscular, cardiovascular, and respiratory systems. Depending on the animal selected, the energetic demands and flux through the oxygen transport system can increase two orders of magnitude from rest to maximal exercise. Thus, animal models in health and disease present the scientist with flexible, powerful, and, in some instances, purpose-built tools to explore the mechanistic bases for physiological function and help unveil the causes for pathological or age-related exercise intolerance. Elegant experimental designs and analyses of kinetic parameters and steady-state responses permit acute and chronic exercise paradigms to identify therapeutic targets for drug development in disease and also present the opportunity to test the efficacy of pharmacological and behavioral countermeasures during aging, for example. However, for this promise to be fully realized, the correct or optimal animal model must be selected in conjunction with reproducible tests of physiological function (e.g., exercise capacity and maximal oxygen uptake) that can be compared equitably across laboratories, clinics, and other proving grounds. Rigorously controlled animal exercise and training studies constitute the foundation of translational research. This review presents the most commonly selected animal models with guidelines for their use and obtaining reproducible results and, crucially, translates state-of-the-art techniques and procedures developed on humans to those animal models.
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Affiliation(s)
- David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - David L Allen
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
| | - Michael Sturek
- Department of Anatomy, Cell Biology and Physiology, Indiana University, Indianapolis, Indiana
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Poole DC, Erickson HH. Exercise-induced pulmonary hemorrhage: where are we now? VETERINARY MEDICINE (AUCKLAND, N.Z.) 2016; 7:133-148. [PMID: 30050846 PMCID: PMC6044800 DOI: 10.2147/vmrr.s120421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
As the Thoroughbreds race for the final stretch, 44 hooves flash and thunder creating a cacophony of tortured air and turf. Orchestrated by selective breeding for physiology and biomechanics, expressed as speed, the millennia-old symphony of man and beast reaches its climax. At nearly 73 kilometers per hour (45 mph) over half a ton of flesh and bone dwarfs its limpet-like jockey as, eyes wild and nostrils flaring, their necks stretch for glory. Beneath each resplendent livery-adorned, latherin-splattered coat hides a monstrous heart trilling at 4 beats per second, and each minute, driving over 400 L (105 gallons) of oxygen-rich blood from lungs to muscles. Matching breath to stride frequency, those lungs will inhale 16 L (4 gallons) of air each stride moving >1,000 L/min in and out of each nostril - and yet failing. Engorged with blood and stretched to breaking point, those lungs can no longer redden the arterial blood but leave it dusky and cyanotic. Their exquisitely thin blood-gas barrier, a mere 10.5 μm thick (1/50,000 of an inch), ruptures, and red cells invade the lungs. After the race is won and lost, long after the frenetic crowd has quieted and gone, that blood will clog and inflame the airways. For a few horses, those who bleed extensively, it will overflow their lungs and spray from their nostrils incarnadining the walls of their stall: a horrifically poignant canvas that strikes at horse racing's very core. That exercise-induced pulmonary hemorrhage (EIPH) occurs is a medical and physiological reality. That every reasonable exigency is not taken to reduce/prevent it would be a travesty. This review is not intended to provide an exhaustive coverage of EIPH for which the reader is referred to recent reviews, rather, after a brief reminder of its physiologic and pathologic bases, focus is brought on the latest developments in EIPH discovery as this informs state-of-the-art knowledge, the implementation of that knowledge and recommendations for future research and treatment.
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Affiliation(s)
- David C Poole
- Department of Anatomy and Physiology,
- Department of Kinesiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA,
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Poole D, Sexton W. Howard H. Erickson: contributions to equine exercise physiology and veterinary medicine. COMPARATIVE EXERCISE PHYSIOLOGY 2016. [DOI: 10.3920/cep160001] [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
For over four and a half decades Howard Erickson has been at the forefront of scientific discovery. As a veterinary cardiovascular specialist with the United States Air Force he made fundamental progress to developing a working artificial heart. Subsequently as a retired US Air Force Colonel and Professor at Kansas State University College of Veterinary Medicine Erickson detected the immensely high pulmonary vascular pressures in the horse during exercise. These observations were essential to resolving the mechanistic bases for exercise-induced arterial hypoxemia and pulmonary haemorrhage (EIPH) that afflict all racehorses. Subsequently, Erickson pioneered the scientific proof-of-concept of the equine Nasal Strip™ which reduces lung damage and epistaxis, and constitutes the only effective non-pharmaceutical treatment for EIPH available today. We owe much of our understanding of equine cardiorespiratory physiology to this remarkable scientist.
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Affiliation(s)
- D.C. Poole
- Departments of Kinesiology, Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - W.L. Sexton
- Department of Physiology, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
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Abstract
Evolutionary forces drive beneficial adaptations in response to a complex array of environmental conditions. In contrast, over several millennia, humans have been so enamored by the running/athletic prowess of horses and dogs that they have sculpted their anatomy and physiology based solely upon running speed. Thus, through hundreds of generations, those structural and functional traits crucial for running fast have been optimized. Central among these traits is the capacity to uptake, transport and utilize oxygen at spectacular rates. Moreover, the coupling of the key systems--pulmonary-cardiovascular-muscular is so exquisitely tuned in horses and dogs that oxygen uptake response kinetics evidence little inertia as the animal transitions from rest to exercise. These fast oxygen uptake kinetics minimize Intramyocyte perturbations that can limit exercise tolerance. For the physiologist, study of horses and dogs allows investigation not only of a broader range of oxidative function than available in humans, but explores the very limits of mammalian biological adaptability. Specifically, the unparalleled equine cardiovascular and muscular systems can transport and utilize more oxygen than the lungs can supply. Two consequences of this situation, particularly in the horse, are profound exercise-induced arterial hypoxemia and hypercapnia as well as structural failure of the delicate blood-gas barrier causing pulmonary hemorrhage and, in the extreme, overt epistaxis. This chapter compares and contrasts horses and dogs with humans with respect to the structural and functional features that enable these extraordinary mammals to support their prodigious oxidative and therefore athletic capabilities.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy and Physiology, Kansas State University, Manhattan, KS, USA.
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Van Erck-Westergren E, Franklin SH, Bayly WM. Respiratory diseases and their effects on respiratory function and exercise capacity. Equine Vet J 2013; 45:376-87. [PMID: 23368813 DOI: 10.1111/evj.12028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 12/02/2012] [Indexed: 12/26/2022]
Abstract
Given that aerobic metabolism is the predominant energy pathway for most sports, the respiratory system can be a rate-limiting factor in the exercise capacity of fit and healthy horses. Consequently, respiratory diseases, even in mild forms, are potentially deleterious to any athletic performance. The functional impairment associated with a respiratory condition depends on the degree of severity of the disease and the equestrian discipline involved. Respiratory abnormalities generally result in an increase in respiratory impedance and work of breathing and a reduced level of ventilation that can be detected objectively by deterioration in breathing mechanics and arterial blood gas tensions and/or lactataemia. The overall prevalence of airway diseases is comparatively high in equine athletes and may affect the upper airways, lower airways or both. Diseases of the airways have been associated with a wide variety of anatomical and/or inflammatory conditions. In some instances, the diagnosis is challenging because conditions can be subclinical in horses at rest and become clinically relevant only during exercise. In such cases, an exercise test may be warranted in the evaluation of the patient. The design of the exercise test is critical to inducing the clinical signs of the problem and establishing an accurate diagnosis. Additional diagnostic techniques, such as airway sampling, can be valuable in the diagnosis of subclinical lower airway problems that have the capacity to impair performance. As all these techniques become more widely used in practice, they should inevitably enhance veterinarians' diagnostic capabilities and improve their assessment of treatment effectiveness and the long-term management of equine athletes.
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Laboratory findings in respiratory fluids of the poorly-performing horse. Vet J 2010; 185:115-22. [PMID: 19481964 DOI: 10.1016/j.tvjl.2009.05.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Revised: 04/30/2009] [Accepted: 05/03/2009] [Indexed: 11/23/2022]
Abstract
Any disorder impairing a performance horse's ability to ventilate its lungs and exchange oxygen compromises exercise performance in any discipline. Since bronchoalveolar lavage was described in horses in the early 1980s, laboratory evaluation of respiratory fluids, along with clinical and functional assessment of the respiratory system, has become a relevant step in the diagnosis of respiratory disease affecting performance. The aim of this review is to provide objective information to assist clinicians in interpreting laboratory findings by (1) summarising published cytological references values in both clinically healthy horses and those with various airway diseases, (2) assessing the influence of physiological circumstances, such as exercise, on the cytological evaluation, (3) discussing the relationship between cytological and microbiological analyses, clinical signs and respiratory function, and (4) suggesting how this latter relationship may affect performance.
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Deaton CM, Brown-Feltner H, Henley WE, Roberts CA, Lekeux P, Schroter RC, Marlin DJ. The effect of inspired gas density on pulmonary artery transmural pressure and exercise induced pulmonary haemorrhage. Equine Vet J 2010:490-4. [PMID: 17402472 DOI: 10.1111/j.2042-3306.2006.tb05593.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
REASONS FOR PERFORMING STUDY Pulmonary capillary stress failure, largely as a result of high pulmonary vascular pressures, has been implicated in the aetiology of EIPH. However, the role of the respiratory system in determining the magnitude of EIPH has received little attention. HYPOTHESIS Horses breathing a gas of greater density than air will exhibit greater transmural pulmonary arterial pressures (TPAP) and more severe EIPH, and horses breathing a gas of lower density than air will exhibit lower TPAP and less severe EIPH, both compared with horses breathing air. METHODS Following a warm-up, 8 Thoroughbred horses were exercised for 1 min at 10, 11 and 12 m/sec (5 degrees incline) breathing air or 21% oxygen/79% helium or 21% oxygen/79% argon in a randomised order. Heart rate, respiratory rate, pulmonary arterial pressure and oesophageal pressure were measured during exercise. Bronchoalveolar lavage fluid (BALF) was collected from the dorsocaudal regions of the left and right lungs 40 min post exercise and red blood cell (RBC) counts were performed. RESULTS The exercise tests induced mild EIPH. Maximum changes in oesophageal pressure were lower on helium-oxygen compared to argon-oxygen (P<0.001). TPAP and median RBC counts did not differ between gas mixtures. BALF RBC counts from the left lung correlated with counts from the right lung (P<0.0001). However BALF RBC counts from the left lung were higher than those from the right lung (P = 0.004). CONCLUSION As alterations in pulmonary arterial and oesophageal pressure caused by changes in inspired gas density were of similar magnitude, TPAP remained unchanged and there was no significant effect on EIPH severity. POTENTIAL RELEVANCE Manipulations that decrease swings in intrapleural pressure may only decrease the degree of EIPH in horses severely affected by the condition.
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Affiliation(s)
- C M Deaton
- Animal Health Trust, Lanwades Park, Kentford, Suffolk, UK
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Epp TS, McDonough P, Padilla DJ, Gentile JM, Edwards KL, Erickson HH, Poole DC. Exercise-induced pulmonary haemorrhage during submaximal exercise. Equine Vet J 2010:502-7. [PMID: 17402474 DOI: 10.1111/j.2042-3306.2006.tb05595.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
REASONS FOR PERFORMING STUDY Maximally exercising horses achieve mean pulmonary artery pressures (Ppa(mean)) that exceed the minimum threshold (75 mmHg) estimated for pulmonary capillary rupture and exercise-induced pulmonary haemorrhage (EIPH). EIPH is not expected to occur during moderate submaximal exercise (i.e. 40-60% VO2max) since Ppa(mean) remains well below this threshold. HYPOTHESIS Prolonged submaximal exercise (trotting) would precipitate locomotory respiratory uncoupling and cause EIPH. This would be present as a result of the most negative intrapleural pressures (as estimated by the minimum oesophageal pressure; Poes(min)) occurring simultaneously with the most positive Ppa (Ppa(peak)) to produce estimated maximal pulmonary artery transmural pressures (PATMPmax) that surpass the EIPH threshold. METHODS Five Thoroughbred horses trotted to fatigue (approximately 25 min) at 5 m/sec on a 10% incline. Ventilation (V(E)), Poes, and Ppa were measured at 5 min intervals, and bronchoalveolar lavage (BAL) red blood cells (RBCs) were quantified 45 min post exercise. RESULTS BAL revealed an increased EIPH (rest: 2.0 +/- 1 x 10(5), exercise: 17 +/- 10 x 10(5) RBCs/ml BALF; P<0.05), despite the highest Ppamean reaching only mean +/- s.e. 55 +/- 3 mmHg, while V(E), tidal volume and Poes(min) approached 70-80% of the values achieved at maximal running speeds (10% incline: 12-13 m/sec) by these same horses. The resulting PATMPmax was well above the level considered causative of EIPH. CONCLUSIONS The finding of significant EIPH during submaximal exercise broadens the spectrum of performance horses susceptible to EIPH and supports studies that suggest that extravascular factors are of primary importance in the aetiology of EIPH. POTENTIAL RELEVANCE Consideration of strategies such as the equine nasal strip for reducing negative extravascular pressures is warranted even for exercise at moderate intensities.
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Affiliation(s)
- T S Epp
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506, USA
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Transverse and dorso-ventral changes in thoracic dimension during equine locomotion. Vet J 2009; 179:370-7. [DOI: 10.1016/j.tvjl.2007.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 10/16/2007] [Accepted: 10/18/2007] [Indexed: 11/20/2022]
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Hoffman AM. Bronchoalveolar lavage: sampling technique and guidelines for cytologic preparation and interpretation. Vet Clin North Am Equine Pract 2008; 24:423-35, vii-viii. [PMID: 18652963 DOI: 10.1016/j.cveq.2008.04.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Bronchoalveolar lavage (BAL) is a method for the recovery of respiratory secretions that line the peripheral airways and alveoli. Overall, BAL is considered very safe and sufficiently sensitive to detect inflammation at the cytologic level. The good correlation between BAL differential cell counts and exercise-induced hypoxemia or lactic acidosis, airway obstruction, or airway responsiveness attests to the relevance of BAL cytology to the structure and function of the equine airways. Thus, an important advantage of BAL over tracheal wash cytology is that BAL cytology relates well to the clinical signs and pathophysiologic consequences of inflammatory airway disease.
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Affiliation(s)
- Andrew M Hoffman
- Tufts University, Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA 01539, USA.
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Evidence supporting exercise-induced pulmonary haemorrhage in racing greyhounds. COMPARATIVE EXERCISE PHYSIOLOGY 2008. [DOI: 10.1017/s147806150891906x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Padilla DJ, Epp TS, McDonough P, Marlin DJ, Erickson HH, Poole DC. Effects of a specific endothelin-1A antagonist on exercise-induced pulmonary haemorrhage (EIPH) in thoroughbred horses. Equine Vet J 2007:198-203. [PMID: 17402418 DOI: 10.1111/j.2042-3306.2006.tb05539.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
REASONS FOR PERFORMING STUDY During high intensity exercise, the very high pulmonary artery pressure (Ppa) experienced by Thoroughbred horses is considered a major factor in the aetiology of exercise-induced pulmonary haemorrhage (EIPH). Recently, endothelin-1 (ET-1), a potent vasoconstrictive hormone, has been found to increase Ppa in horses at rest via binding to its ET-1A receptor subtype. In addition, plasma concentrations of ET-1 are increased in horses during and after high intensity exercise. HYPOTHESIS If ET-1 increases Ppa during exercise in the horse, administration of a specific ET-1A antagonist would decrease Ppa and therefore EIPH. METHODS Saline (CON) or an ET-1A receptor antagonist, TBC3214 (3 mg/kg bwt i.v.; ANTAG) was administered to horses 1 h prior to maximal incremental exercise on a high-speed treadmill. Gas exchange measurements were made breath-by-breath and blood samples collected during each 1 min stage to determine blood gases, acid-base status and cardiac output. EIPH was determined via bronchoalveolar lavage (BAL) approximately 30 min after exercise. RESULTS The time to fatigue, gas exchange and cardiovascular responses were not different between groups (P>0.05). Resting and peak Ppa did not differ significantly between treatments. Most importantly, ANTAG did not decrease EIPH. CONCLUSIONS These results do not support a deterministic role for ET-1 in the increased Ppa and therefore EIPH, during maximal exercise in the equine athlete. POTENTIAL RELEVANCE Treatment with an ET-1A receptor antagonist does not appear to be a viable therapeutic intervention in the prevention of EIPH.
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Affiliation(s)
- D J Padilla
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506, USA
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