Extravascular lung water in the exercising horse.
Abstract: Seven Standardbred horses were exercised on a treadmill at speeds (approximately 12 m/s) producing maximal heart rate, hypoxemia, and a mean pulmonary arterial pressure of approximately 75 mmHg. Extravascular lung water was measured by using transients in temperature and electrical impedance of the blood caused by a bolus injection of cold saline solution. Lung water was approximately 3 ml/kg body wt when standing but did not increase significantly with exertion. We conclude that any increase in fluid extravasation from the pulmonary hypertension accumulates in the lung at a level that is less than that detectable by this method. At maximal exertion, the volume of blood measured between the jugular vein and the carotid artery increased by approximately 8 ml/kg, and the actively circulating component of the systemic blood volume increased by approximately 17 ml/kg with respect to corresponding values obtained when walking before exertion. These volume increases, reflecting recruitment and dilatation of capillaries, increase the area for respiratory gas exchange and offset the reduced transit times that would otherwise be imposed by the approximately eightfold increase in cardiac output at maximal exertion.
Publication Date: 2001-11-22 PubMed ID: 11717203DOI: 10.1152/jappl.2001.91.6.2442Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This study investigates how intensive exercise affects the buildup of fluid outside the blood vessels in the lungs of horses, with the findings suggesting that any such increase due to high blood pressure in the lungs is undetectable by the method used in the study. Additionally, the study finds that vigorous exercise significantly increases the blood volume in certain areas and the amount of blood actively circulating in the system.
Experiment Methodology
- The study was conducted on seven Standardbred horses.
- The horses were made to exercise on a treadmill at speeds roughly 12 meters per second. This results in maximal heart rate, low oxygen levels in blood (hypoxemia), and an average pulmonary arterial pressure of around 75 mmHg.
- The researchers measured the extravascular lung water, which is the fluid outside the blood vessels in the lungs, using changes in temperature and electrical impedance of the blood. This was triggered by an injection of cold saline solution.
Research Findings
- When the horses were standing, the lung water was about 3 milliliters per kilogram body weight. This did not significantly increase with exertion.
- Therefore, it was concluded that any increase in fluid seepage due to pulmonary hypertension is less than what the used method can detect.
- At the point of maximum effort, the volume of blood measured between the jugular vein and the carotid artery increased by about 8 ml/kg.
- Additionally, the amount of blood actively circulating in the system increased by approximately 17 ml/kg compared to values obtained when walking before exertion.
Implications of the Study
- The increases in blood volume indicate recruitment and dilation of capillaries, which increase the area available for respiratory gas exchange.
- This larger area compensates for the reduced transit times that could otherwise be imposed due to the approximately eightfold increase in cardiac output at maximum exertion. This reveals an adaptive mechanism to maintain efficient gas exchange despite high exercise intensity.
Cite This Article
APA
Wilkins PA, Gleed RD, Krivitski NM, Dobson A.
(2001).
Extravascular lung water in the exercising horse.
J Appl Physiol (1985), 91(6), 2442-2450.
https://doi.org/10.1152/jappl.2001.91.6.2442 Publication
Researcher Affiliations
- Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
MeSH Terms
- Animals
- Blood Flow Velocity
- Blood Volume
- Body Water / metabolism
- Female
- Hemodynamics
- Horses / physiology
- Hypertension, Pulmonary / complications
- Hypertension, Pulmonary / etiology
- Hypertension, Pulmonary / physiopathology
- Lung / metabolism
- Male
- Motor Activity / physiology
- Pulmonary Edema / etiology
Citations
This article has been cited 3 times.- Vengust M, Staempfli H, Viel L, Swenson ER, Heigenhauser G. Acetazolamide attenuates transvascular fluid flux in equine lungs during intense exercise. J Physiol 2013 Sep 15;591(18):4499-513.
- MacNutt MJ, Guenette JA, Witt JD, Yuan R, Mayo JR, McKenzie DC. Intense hypoxic cycle exercise does not alter lung density in competitive male cyclists. Eur J Appl Physiol 2007 Apr;99(6):623-31.
- Vengust M, Staempfli H, Viel L, Heigenhauser G. Transvascular fluid flux from the pulmonary vasculature at rest and during exercise in horses. J Physiol 2006 Jan 15;570(Pt 2):397-405.
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