Functional and compositional changes in pulmonary surfactant in response to exercise.
Abstract: Pulmonary surfactant from bronchoalveolar lavages was obtained from 2 groups of horses. A control group consisting of 6 healthy racehorses that were paddock-rested and lavaged weekly for 6 consecutive weeks were compared with an experimental group of 10 healthy racehorses, lavaged weekly the same period, consisting of a 5 week incremental-intensity treadmill training programme and one week post training paddock rest. Phospholipid content of lavage fluid was determined indirectly by phosphorus assay, and surfactant functional activity was determined by bubble surfactometry. Total cell counts and differential cell percentages of lavage fluid were adjusted to reflect the dilution of alveolar epithelial lining fluid (ELF) using the lavage/serum urea ratio, and data were analysed per volume of ELF. There was no change in phospholipid content for either group, but some horses had consistently greater amounts than did others, ranging from 17.2-64.4 micrograms/microliter. From the exercised group ELF had both increased nucleated cell numbers due to increased macrophage numbers, and increased numbers of erythrocytes. Surface tension increased significantly over the exercise protocol, but not in controls. Functional activity of surfactant varied between horses, independent of phospholipid content, with average values for individuals ranging 10.5-29.5 mN/m. We conclude that exercise of sufficient intensity to induce intrapulmonary haemorrhage also leads to functional decrease in surfactant activity, without affecting phospholipid content. This study also indicates that functional differences in surfactant exist between horses and may be a risk factor for development of exercise-induced pulmonary haemorrhage.
Publication Date: 2000-02-05 PubMed ID: 10659224DOI: 10.1111/j.2042-3306.1999.tb05190.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates changes in pulmonary surfactant – a substance important for lung function – in racehorses in response to exercise, and finds that intense exercise leading to lung damage could also reduce surfactant functionality without affecting its composition, hinting at potential risk factors for exercise-induced lung bleeding.
Study Design
- The experiment involved two groups of horses – a control group of 6 healthy racehorses and a group of 10 healthy racehorses that followed a 5-week treadmill training with one week of rest.
- Both groups were “lavage” – a procedure for washing out an organ or body cavity – weekly for 6 years.
- The researchers primarily measured phospholipid levels through a phosphorous assay, as phospholipids are a crucial part of the surfactant.
- The functionality of the surfactant was tested via bubble surfactometry, a method that tests the lowering of surface tension by surfactants.
Findings of the Study
- Both groups of horses showed no change in phospholipid content, though some horses had a higher amount ranging from 17.2-64.4 micrograms/microliter.
- In the group that underwent exercise, there was an increase in the number of nucleated cells due to increased macrophage numbers and increased numbers of erythrocytes or red blood cells.
- Surface tension, indicating surfactant functionality, increased significantly in the exercise group, but not in the control group.
- Surfactant functional activity varied between horses regardless of phospholipid content, with average values ranging from 10.5-29.5 mN/m.
Conclusions
- Intense exercise that caused intrapulmonary haemorrhage or lung bleeding also appeared to lead to a decrease in surfactant functionality, even though it did not change the phospholipid content of the surfactant.
- The research also brings out potential risk factors for exercise-induced pulmonary haemorrhage, which is a condition often affecting racehorses. Surfactant functionality, that varied between horses independent of phospholipid content, could potentially contribute to this condition.
Cite This Article
APA
Morrison KE, Slocombe RF, McKane SA, Dargaville PA.
(2000).
Functional and compositional changes in pulmonary surfactant in response to exercise.
Equine Vet J Suppl(30), 62-66.
https://doi.org/10.1111/j.2042-3306.1999.tb05190.x Publication
Researcher Affiliations
- School of Veterinary Science, University of Melbourne, Veterinary Clinical Centre, Werribee, Victoria, Australia.
MeSH Terms
- Animals
- Bronchoalveolar Lavage / veterinary
- Epithelial Cells
- Erythrocyte Count / veterinary
- Horses / physiology
- Leukocyte Count / veterinary
- Physical Conditioning, Animal / physiology
- Protein Conformation
- Pulmonary Surfactants / physiology
Citations
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