| Changes in arterial, mixed venous and intraerythrocytic concentrations of ions in supramaximally exercising horses. | |
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MedLine Citation:
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PMID: 17402435 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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REASONS FOR PERFORMING STUDY: Horses experience major perturbations in acid-base balance during supramaximal exercise. Ion movement in and out of erythrocytes (RBCs) is believed to be important in maintaining acid-base balance but it is unclear as to the extent to which this happens, nor how it affects single measurements of ion concentrations in arterial and venous blood. OBJECTIVES: To clarify the role RBCs play in mitigating perturbations in acid-base balance during high speed exercise in horses, and to describe associated differences in arterial (a) and mixed venous (v) concentrations of key ions. METHODS: Six exercise-trained Thoroughbreds galloped to fatigue at speeds calculated to have an oxygen demand that was 115% of the VO2max. Blood samples (a and v) were collected pre-exercise, during warm-up, at fatigue, and immediately post exercise. Packed cell volume (PCV), pH, PCO2, and plasma concentrations of bicarbonate (HCOP3-), chloride (Cl-), sodium (Na+), potassium (K+), and lactate (Lac-) and strong ion difference (SID) were determined, and RBC concentrations of Lac- and electrolytes calculated for each sample. Data were analysed using a 2-way ANOVA for repeated measures testing for effects of sampling time and site (P<0.05). RESULTS: Plasma and RBC [Cl-] were increased with hypercapnoea and acidaemia. [HCO3-]v was greater than pre-exercise values at fatigue, although [HCO3l]a was lower. Hyperkalaemia and decreased RBC [K+] were evident at fatigue, as was an increased RBC [Na+]. Plasma [K+] started to decrease as soon as exercise ceased and Na+ began to move back onto RBCs in exchange for K+. Concentrations of all measures of Lac- rose from fatigue to post exercise. The SID decreased with exercise and was higher in v at fatigue and post exercise, reflecting the decrease in pH. CONCLUSIONS: RBCs act as a repository for lactate, and therefore the increase in PCV facilitates the maintenance of the muscle to plasma Lac- diffusion gradient during exercise. POTENTIAL RELEVANCE: This serves to keep intramuscular [Lac-] lower than it would otherwise be and, because of the link between Lac- accumulation, pH decrease and the onset of fatigue, may help delay the onset of fatigue. |
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Authors:
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W M Bayly; J K Kingston; J A Brown; R D Keegan; S A Greene; R H Sides |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Equine veterinary journal. Supplement Volume: - ISSN: - ISO Abbreviation: Equine Vet J Suppl Publication Date: 2006 Aug |
Date Detail:
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Created Date: 2007-04-03 Completed Date: 2007-05-02 Revised Date: 2007-05-18 |
Medline Journal Info:
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Nlm Unique ID: 9614088 Medline TA: Equine Vet J Suppl Country: England |
Other Details:
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Languages: eng Pagination: 294-7 Citation Subset: IM |
Affiliation:
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Department of Veterinary Clinical Sciences, College of Veterinary Medicine. Washington State University, Pullman, Washington 99164-6610, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acid-Base Equilibrium
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physiology* Animals Bicarbonates / blood Blood Chemical Analysis / veterinary Blood Gas Analysis / veterinary Carbon Dioxide / blood Chlorides / blood Electrolytes / blood* Erythrocytes / metabolism* Hematocrit / veterinary* Horses / blood* Hydrogen-Ion Concentration Lactic Acid / blood* Oxygen Consumption Physical Conditioning, Animal / physiology* Potassium / blood Sodium / blood |
| Chemical | |
Reg. No./Substance:
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0/Bicarbonates; 0/Chlorides; 0/Electrolytes; 124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid; 7440-09-7/Potassium; 7440-23-5/Sodium |
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