Journal article
Effect of prolonged heavy exercise on pulmonary gas exchange in horses
Journal of applied physiology (1985), Vol.84(5), pp.1723-1730
05/01/1998
Handle:
https://hdl.handle.net/2376/104421
PMID: 9572823
Abstract
During short-term maximal exercise, horses have impaired pulmonary gas exchange, manifested by diffusion limitation and arterial hypoxemia, without marked ventilation-perfusion (V˙a/Q˙) inequality. Whether gas exchange deteriorates progressively during prolonged submaximal exercise has not been investigated. Six thoroughbred horses performed treadmill exercise at ∼60% of maximal oxygen uptake until exhaustion (28–39 min). Multiple inert gas, blood-gas, hemodynamic, metabolic rate, and ventilatory data were obtained at rest and 5-min intervals during exercise. Oxygen uptake, cardiac output, and alveolar-arterial[Formula: see text] gradient were unchanged after the first 5 min of exercise. Alveolar ventilation increased progressively during exercise, from increased tidal volume and respiratory frequency, resulting in an increase in arterial[Formula: see text] and decrease in arterial[Formula: see text]. At rest there was minimalV˙a/Q˙inequality, log SD of the perfusion distribution (log SDQ˙) = 0.20. This doubled by 5 min of exercise (log SDQ˙ = 0.40) but did not increase further. There was no evidence of alveolar-end-capillary diffusion limitation during exercise. However, there was evidence for gas-phase diffusion limitation at all time points, and enflurane was preferentially overretained. Horses maintain excellent pulmonary gas exchange during exhaustive, submaximal exercise. AlthoughV˙a/Q˙inequality is greater than at rest, it is less than observed in most mammals and the effect on gas exchange is minimal.
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Details
- Title
- Effect of prolonged heavy exercise on pulmonary gas exchange in horses
- Creators
- S. R Hopkins - Division of Physiology, Department of Medicine, University of California San Diego, La Jolla, California 92093-0623W. M Bayly - Department of Veterinary Clinical Sciences, Washington State University, Pullman, Washington 99164; andR. F Slocombe - School of Veterinary Science, University of Melbourne, Werribee, Victoria 3030, AustraliaH Wagner - Division of Physiology, Department of Medicine, University of California San Diego, La Jolla, California 92093-0623P. D Wagner - Division of Physiology, Department of Medicine, University of California San Diego, La Jolla, California 92093-0623
- Publication Details
- Journal of applied physiology (1985), Vol.84(5), pp.1723-1730
- Identifiers
- 99900546769301842
- Language
- English
- Resource Type
- Journal article