Plasma volume and ions during exercise in cool, dry; hot, dry; and hot, humid conditions.
Abstract: We studied the effects of heat and relative humidity (RH) on plasma volume (PV) and ion responses to submaximal exercise and 60 min recovery in Thoroughbreds. Five horses were exercised at 50% of peak VO2 in cool, dry (CD, T = 22 degrees C, RH = 45-55%), and hot, humid (HH, T = 30-34 degrees C, RH = 80-85%) conditions until a pulmonary artery temperature of 41.5 degrees C was reached. Blood was obtained from the carotid artery. Body mass was measured at rest and after 30 min of recovery. The thermal conditions had no effect on the PV and ion responses during exercise and initial 30 min of recovery. Exercise resulted in an 8.5% decrease in PV within the first 2 min and, in the absence of changes in plasma [Na+] and [Cl-], was responsible for a 150 to 185 mmol decrease in plasma Na+ and Cl- contents. The decrease in PV was responsible for about 50% of the increase in packed cell volume (37% at rest; 51% at 2 min of exercise). Plasma [K+] and K+ content increased rapidly during the first 2 min of exercise. With cessation of exercise, plasma [K+] declined with a half time of about 2 min; recovery of PV and plasma Na+ and Cl- contents occurred with a half time of 10-15 min, with nearly complete recovery by 30 min. In the HD trial, between 30 and 60 min of recovery there were further decreases in PV and ion contents. It is concluded that with this exercise protocol, thermal stress had minimal influence on the rate and magnitude of exercise-induced changes in PV and ion contents. However, thermal stress during recovery from exercise may impede the restoration of PV and ion contents.
Publication Date: 1995-11-01 PubMed ID: 8933096DOI: 10.1111/j.2042-3306.1995.tb05019.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research analyzed the influence of varying thermal environments (cool, dry; hot, dry; and hot, humid conditions) on the variations in plasma volume and ion levels during and after submaximal exercise in horses. The study found that thermal stress during recovery may influence the restoration of plasma volume and ion levels, but has minimal effect during exercise itself.
Methodology
- Five Thoroughbred horses were subjected to exercise under three different climatic conditions: cool, dry (CD); hot, dry (HD); and hot, humid (HH).
- The exercise was conducted at 50% of peak VO2 until the horses reached a specific core body temperature (pulmonary artery temperature of 41.5 degrees C).
- Carotid artery blood samples were taken for investigation and the horses’ body mass was measured at rest and after 30 minutes of recovery.
Findings
- The thermal conditions did not have any significant effect on the plasma volume and ion responses during exercise and the initial 30 minutes of recovery.
- Exercise resulted in an 8.5% decrease in plasma volume within the first 2 minutes, lowering plasma Na+ and Cl- contents by 150 to 185 mmol, independent of any changes in plasma [Na+] and [Cl-].
- The decrease in plasma volume accounted for about 50% of the increase in packed cell volume.
- Plasma [K+] and K+ content increased quickly during the first 2 minutes of exercise, but decreased swiftly after cessation of exercise.
- The recovery of plasma volume and plasma Na+ and Cl- contents had a half time of around 10-15 minutes, with nearly total recovery by 30 minutes.
- In the hot, dry trial, additional decreases in plasma volume and ion contents were observed between 30 and 60 minutes of recovery.
Conclusion
- It was concluded that while thermal stress did not considerably impact the rate and magnitude of exercise-induced changes in plasma volume and ion contents, it might affect the restoration of these factors during recovery period after exercise.
Cite This Article
APA
Lindinger MI, Geor RJ, Ecker GL, McCutcheon LJ.
(1995).
Plasma volume and ions during exercise in cool, dry; hot, dry; and hot, humid conditions.
Equine Vet J Suppl(20), 133-139.
https://doi.org/10.1111/j.2042-3306.1995.tb05019.x Publication
Researcher Affiliations
- School of Human Biology, University of Guelph, Ontario, Canada.
MeSH Terms
- Animals
- Blood Proteins / analysis
- Body Water / metabolism
- Electrolytes / blood
- Hematocrit / veterinary
- Horses / blood
- Horses / physiology
- Hot Temperature
- Humidity
- Physical Conditioning, Animal / physiology
- Plasma Volume
Citations
This article has been cited 1 times.- Lindinger MI, Waller AP. Physicochemical Analysis of Mixed Venous and Arterial Blood Acid-Base State in Horses at Core Temperature during and after Moderate-Intensity Exercise.. Animals (Basel) 2022 Jul 22;12(15).
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