Document Detail


Respiratory mechanics of horses during stepwise treadmill exercise tests, and the effect of clenbuterol pretreatment on them.
MedLine Citation:
PMID:  1449458     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Normal Standardbred horses were given an incremental exercise test on a horizontal treadmill to evaluate the influence of exercise on gas exchange, resistance, dynamic compliance and inertance of the respiratory system. The exercise test consisted of 2 min exercise steps at each of the following speeds: 2.4 m/sec (walk), 4.5 m/sec (slow trot), 7.0 m/sec (fast trot) and 10 m/sec (gallop). At rest and after 1 min of exercise at each step, airflow, tidal volume, respiratory frequency, pharyngeal, mid-oesophageal and transdiaphragmatic pressures and arterial blood gas tensions were measured. The same horses were subsequently treated intravenously with clenbuterol (0.8 microgram/kg) and an identical exercise test and measurement performed 10 min after clenbuterol injection. In response to exercise, there were large increases in tidal volume, respiratory frequency, airflow and pressures. Exercise was associated with a decrease in upper airway resistance but total pulmonary resistance was unchanged. Exercise did not alter inertance or dynamic compliance, horses became hypoxaemic, and at 10 m/sec (galloping) also developed hypercarbia. Treatment with clenbuterol did not alter any of these measurements in response to exercise. These data suggest that dilation of upper airways occurs during exercise, and that inertial forces are important in strenuously exercising horses and may influence the accuracy of dynamic compliance determinations at high exercise intensities.
Authors:
R F Slocombe; G Covelli; W M Bayly
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Australian veterinary journal     Volume:  69     ISSN:  0005-0423     ISO Abbreviation:  Aust. Vet. J.     Publication Date:  1992 Sep 
Date Detail:
Created Date:  1992-12-30     Completed Date:  1992-12-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370616     Medline TA:  Aust Vet J     Country:  AUSTRALIA    
Other Details:
Languages:  eng     Pagination:  221-5     Citation Subset:  IM; S    
Affiliation:
School of Veterinary Science, University of Melbourne, Parkville, Victoria.
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MeSH Terms
Descriptor/Qualifier:
Airway Resistance
Animals
Bicarbonates / blood
Clenbuterol / pharmacology*
Exercise Test / veterinary
Female
Horses / physiology*
Male
Oxygen / blood
Physical Exertion / physiology*
Pressure
Respiration* / drug effects
Tidal Volume
Chemical
Reg. No./Substance:
0/Bicarbonates; 37148-27-9/Clenbuterol; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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