Alterations in plasma volume, plasma constituents, renin activity and aldosterone induced by maximal exercise in the horse.
Abstract: Plasma volume (PV) decreased by 13 per cent following the completion of 1,000 m of maximal exercise in the horse. This study demonstrated that the critical reduction in PV following maximal exercise occurred within 10 mins of completion of exercise, as previously reported in man. Total plasma protein (TPP) increased by 23 per cent at 2 and 5 mins, and by 21 per cent at 10 mins post exercise. Therefore, it does not appear to be an accurate measurement to assess the degree of PV contraction in the horse. Protein was apparently added to the intravascular space either during or following exercise. The changes in osmolality correlated strongly with those in sodium, which is the primary determinant of alterations in plasma tonicity. The increase in osmolality (12 per cent) was similar to the reduction in PV (13 per cent) concluding that a transient hypotonic fluid loss had occurred. The increase in plasma renin activity (PRA) following maximal exercise was followed by an increase in aldosterone (ALD) concentration in both magnitude and time course. Alterations in PV should be considered when interpreting electrolyte and serum enzyme activity data collected following maximal exercise.
Publication Date: 1990-06-01 PubMed ID: 9259811DOI: 10.1111/j.2042-3306.1990.tb04739.xGoogle Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article explores the changes in plasma volume, plasma constituents, renin activity, and the aldosterone hormone observed in horses following intense exercise, particularly noting a noteworthy decrease in plasma volume, and increases in total plasma protein, osmolality, plasma renin activity, and aldosterone concentration.
Plasma Volume Reduction
- The study found that plasma volume in the horses significantly reduced by 13% after completing 1,000 meters of maximum exercise.
- This considerable reduction took place mostly within the first 10 minutes following exercise completion. This finding is consistent with previous research carried out on humans.
Total Plasma Protein Increase
- Total plasma protein increased noticeably, specifically by 23% at 2 and 5 minutes, and 21% at 10 minutes after exercise.
- Due to these significant variations, the authors state that total plasma protein levels may not provide an accurate measure of plasma volume contractions in horses.
- It suggests that protein was added to the intravascular space either during or after exercise.
Osmolality Correlation
- The changes in plasma osmolality, or concentration of the plasma, were found to be strongly correlated with changes in sodium levels. Sodium is the primary determinant of alterations in plasma tonicity or osmotic pressure.
- The increase in plasma osmolality was just as proportionate (12%) as the reduction in plasma volume (13%), leading to a conclusion that a transient, or temporary, loss of hypotonic fluid had taken place.
Plasma Renin Activity and Aldosterone Concentration
- The increase in plasma renin activity, an enzyme that plays a fundamental role in the body’s renin-angiotensin-aldosterone system, following maximum exercise was then succeeded by an increase in the aldosterone hormone concentration.
- The increase in both the plasma renin activity and aldosterone concentration occurred in both magnitude and time course.
Implications for Interpretation
- The researchers stress that, when assessing electrolyte and serum enzyme activity data collected after maximum exercise, such plasma volume changes must be taken into account.
- This is because the changes in plasma volume can strongly impact these measurements and any related interpretations.
Cite This Article
APA
Masri M, Freestone JF, Wolfsheimer KJ, Shoemaker K.
(1990).
Alterations in plasma volume, plasma constituents, renin activity and aldosterone induced by maximal exercise in the horse.
Equine Vet J Suppl(9), 72-77.
https://doi.org/10.1111/j.2042-3306.1990.tb04739.x Publication
Researcher Affiliations
- School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803-8422, USA.
MeSH Terms
- Aldosterone / blood
- Animals
- Blood Proteins / analysis
- Blood Volume / physiology
- Female
- Heart Rate / physiology
- Hematocrit
- Horses / physiology
- Male
- Osmolar Concentration
- Physical Conditioning, Animal / physiology
- Radioimmunoassay / methods
- Radioimmunoassay / veterinary
- Renin / blood
- Renin-Angiotensin System / physiology
- Rest / physiology
- Sodium / blood
- Time Factors
Citations
This article has been cited 4 times.- Ekman S, Lindahl A, Rüetschi U, Jansson A, Björkman K, Abrahamsson-Aurell K, Björnsdóttir S, Löfgren M, Hultén LM, Skiöldebrand E. Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses. Equine Vet J 2019 Sep;51(5):674-680.
- Holbrook T, Hernandez J, McCarrel T, Lester G, Sleeper M, Domenig O, Adin D. Renin-Angiotensin-Aldosterone System Profiling in Horses Before and After Exercise. J Vet Intern Med 2025 Mar-Apr;39(2):e70036.
- Titotto AC, Santos MM, Ramos GV, Adão MDS, Benvenuto GV, De Lacerda LCC, Lisbôa JAN, Lacerda-Neto JC. Effect of Lactate Minimum Speed-Guided Training on the Fluid, Electrolyte and Acid-Base Status of Horses. Animals (Basel) 2023 Oct 21;13(20).
- Giers J, Bartel A, Kirsch K, Müller SF, Horstmann S, Gehlen H. Blood-Based Markers for Skeletal and Cardiac Muscle Function in Eventing Horses before and after Cross-Country Rides and How They Are Influenced by Plasma Volume Shift. Animals (Basel) 2023 Oct 5;13(19).
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