Changes in arterial, mixed venous and intraerythrocytic concentrations of ions in supramaximally exercising horses.
Abstract: 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. Objective: 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. Conclusions: 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.
Publication Date: 2007-04-04 PubMed ID: 17402435DOI: 10.1111/j.2042-3306.2006.tb05556.xGoogle Scholar: Lookup
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- Journal Article
Summary
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The research is a study to understand the role of red blood cells (RBCs) in maintaining acid-base balance in horses during high-speed exercise and the changes in arterial and mixed venous concentrations of key ions.
Objective of the Research
- The main aim of this study is to analyze and determine the effect of RBCs in upholding the acid-base balance, critically important during high-intensity exercise in horses. Additionally, the research is concerned with describing the variations in arterial (a) and mixed venous (v) concentrations of key ions affected by such exercise.
Methodology
- Six well-trained thoroughbreds were made to gallop to the point of fatigue at speed, requiring an oxygen demand that was 115% of their maximum oxygen uptake (VO2Max).
- Both arterial and venous blood samples were collected before exercise, during warm-up, at fatigue, and post exercise.
- The study evaluated Packed cell volume (PCV), pH, PCO2, plasma concentrations of several ions including bicarbonate (HCO3-), chloride (Cl-), sodium (Na+), potassium (K+), and lactate (Lac-), and strong ion difference (SID), and also calculated RBC concentrations of Lac- and electrolytes for each sample.
- Data analysis was done using a 2-way ANOVA for repeated measures to test for effects of sampling time and site.
Results
- The research established that plasma and RBC concentrations of chloride (Cl-) increased with hypercapnia (excess carbon dioxide) and acidemia (abnormally high acidity of the blood).
- Veinous bicarbonate concentration (HCO3- v) was found to be higher than pre-exercise values at the point of fatigue, despite arterial bicarbonate concentration (HCO3- a) being lower.
- Hyperkalemia (high potassium levels in the blood) and decreased RBC potassium concentration were observed at fatigue, along with an increased RBC concentration of sodium.
- As soon as exercise ceased, plasma potassium concentration started to decline and sodium began to move back onto RBCs in exchange for potassium.
- Lactate concentrations rose from fatigue to post exercise, and the strong ion difference (SID) decreased with exercise and was higher in venous blood at fatigue and post exercise, reflecting the decrease in pH.
Conclusions
- The researchers concluded that RBCs act as a reservoir for lactate, and therefore the increase in packed cell volume (PCV) plays a crucial role in maintaining the muscle to plasma lactate diffusion gradient during exercise.
- This mechanism helps to keep the intramuscular concentration of lactate lower than it would otherwise be, and because of the correlation between lactate accumulation, pH decrease and the onset of fatigue, this might help in delaying the onset of fatigue in horses during rigorous exercise.
Cite This Article
APA
Bayly WM, Kingston JK, Brown JA, Keegan RD, Greene SA, Sides RH.
(2007).
Changes in arterial, mixed venous and intraerythrocytic concentrations of ions in supramaximally exercising horses.
Equine Vet J Suppl(36), 294-297.
https://doi.org/10.1111/j.2042-3306.2006.tb05556.x Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine. Washington State University, Pullman, Washington 99164-6610, USA.
MeSH Terms
- Acid-Base Equilibrium / 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
Citations
This article has been cited 2 times.- Stefánsdóttir GJ, Gunnarsson V, Roepstorff L, Ragnarsson S, Jansson A. The effect of rider weight and additional weight in Icelandic horses in tölt: part I. Physiological responses. Animal 2017 Sep;11(9):1558-1566.
- Sanigavatee K, Poochipakorn C, Huangsaksri O, Wonghanchao T, Yalong M, Poungpuk K, Thanaudom K, Chanda M. Hematological and physiological responses in polo ponies with different field-play positions during low-goal polo matches. PLoS One 2024;19(5):e0303092.
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