Effects of dehydration and rehydration on plasma vasopressin and aldosterone in horses.
Abstract: We have investigated the change in plasma vasopressin and aldosterone concentrations in Namib (desert-adapted) and in control horses from a subtropical region, during an acute 12% dehydration and during rehydration, while food was available. During dehydration, vasopressin concentrations increased significantly in both groups of horses, but the increase was significantly greater in Namib horses than in control horses. During rehydration, vasopressin levels fell, but fell significantly less in Namib horses. The change in vasopressin concentration correlated significantly with plasma osmolality (r = 0.88, p < 0.001), and the relationship between these two variables was the same for both groups of horses during the dehydrated and rehydrated states. Aldosterone concentrations fell up to 48-h dehydration in both groups, but decreased significantly more in desert horses. From 48-h dehydration and during rehydration, aldosterone concentrations increased and the increase was sustained longer in Namib than in control horses. Changes in plasma osmolality did not correlate significantly with changes in aldosterone concentration. There were significant correlations between faecal moisture (%) and both vasopressin and aldosterone concentrations (r = -0.72, p < 0.008; r = 0.80, p < 0.002, respectively). During the 12% dehydration, the Namib horses sustained higher plasma osmolalities and consequently vasopressin levels than the control horses. We conclude that plasma osmolality in conjunction with these two hormones plays a significant role in water homeostasis in horses.
Publication Date: 1993-08-01 PubMed ID: 8372114DOI: 10.1016/0031-9384(93)90103-mGoogle Scholar: Lookup
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- Journal Article
Summary
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The research studied the effect of dehydration and rehydration on the concentration of plasma vasopressin and aldosterone in two different types of horses. It was found that both hormones play a significant role in maintaining the balance of water in horses.
Methodology
- The experiment involved Namib horses (desert-adapted) and control horses from a subtropical region. An acute 12% dehydration was induced in both groups and then they were rehydrated, all while food was available.
- The concentration of plasma vasopressin and aldosterone were assessed throughout the dehydration and rehydration process.
Results
- In the course of dehydration, vasopressin concentrations significantly increased in both groups of horses. However, the increase was notably greater in Namib horses as compared to control horses.
- When rehydrated, vasopressin levels decreased but once again, the reduction was significantly less in Namib horses. Vasopressin concentration had a significant correlation with plasma osmolality (the concentration of particles in a solution, or the solution’s pulling power).
- The concentration of aldosterone fell during up to 48 hours of dehydration in both groups but the decrease was significantly more in desert-adapted horses. From 48 hours of dehydration and during rehydration, aldosterone levels increased and this increase sustained longer in Namib horses. However, the changes in plasma osmolality did not correlate significantly with changes in aldosterone concentration.
- Significant correlations were found between faecal moisture and both vasopressin and aldosterone concentrations, indicating these hormones’ role in maintaining body water levels.
Conclusion
- Different horse breeds showed varying hormone responses during periods of dehydration and rehydration, likely due to differences in their natural habitats. The Namib horses exhibited higher plasma osmolalities and consequently higher vasopressin levels than the control horses during the 12% dehydration.
- It was concluded that plasma osmolality in conjunction with the hormones vasopressin and aldosterone play a significant role in water homeostasis in horses. This has likely allowed the desert-adapted horses to evolve mechanisms to withstand harsh conditions and maintain adequate hydration.
Cite This Article
APA
Sneddon JC, Van Der Walt J, Mitchell G, Hammer S, Taljaard JJ.
(1993).
Effects of dehydration and rehydration on plasma vasopressin and aldosterone in horses.
Physiol Behav, 54(2), 223-228.
https://doi.org/10.1016/0031-9384(93)90103-m Publication
Researcher Affiliations
- Department of Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Republic of South Africa.
MeSH Terms
- Acclimatization / physiology
- Aldosterone / blood
- Animals
- Desert Climate
- Drinking / physiology
- Female
- Horses / blood
- Male
- Vasopressins / blood
- Water Deprivation / physiology
- Water-Electrolyte Balance / physiology
Citations
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