Pulmonary vascular pressures of thoroughbreds increase rapidly and to a higher level with rapid onset of high-intensity exercise than slow onset.
Previous studies of pulmonary vascular pressures have utilised gradual incremental step exercise protocols, but in competitive racing at the track, horses perform rapid acceleration high-intensity exercise. The rate of rise in pulmonary vascular pressures under conditions of quick onset high-intensity exercise is unknown. Catheter mounted manometers, whose in vivo signals were matched with pressure signals obtained via transducers connected to fluid-filled lumens from same cardiovascular sites, were used to compare right heart and pulmonary vascular pressures in 8 healthy Thoroughbreds performing 2 separate exercise protocols on a high speed treadmill (gradually incremental vs. rapid acceleration exercise protocol where the belt speed was raised from 8 m/s to 15 m/s in 8 s). Heart rate, right atrial and pulmonary vascular pressures at rest were similar for the 2 protocols. Rapid acceleration of horses from 8 to 15 m/s was attended by an equally rapid escalation in the right heart and pulmonary vascular pressures such that these pressures reached their zenith as belt speed approached 15 m/s. Although exercise at 15 m/s resulted in similar heart rate in the 2 protocols, the mean +/- s.e. values of mean right atrial pressure, mean pulmonary artery pressure, mean pulmonary artery wedge pressure and mean pulmonary capillary pressure (91.5 +/- 3.9 mmHg) in the rapid acceleration exercise were significantly (P < 0.05) higher than respective values at 15 m/s in the gradual incremental step exercise protocol.(ABSTRACT TRUNCATED AT 250 WORDS)
Manohar
M
M
Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign 61801.
D000818:Animals; D006339:Heart Rate / Q000502:physiology; D006736:Horses / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000009:adverse effects* / Q000379:methods*; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D013223:Statistics as Topic; D013997:Time Factors