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Published on: September 17, 2015
Influence of frusemide on dynamic cardiac variables during exercise
I Langsetmo1, G E Weigle, H H Erickson
1Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan 66506, USA.
Equine Veterinary Journal. Supplement
|February 5, 2000
Summary
Frusemide effectively lowers high right atrial pressures in exercising horses, but does not significantly alter right ventricular relaxation dynamics. This suggests the drug
Area of Science:
- Equine Cardiology
- Exercise Physiology
- Pharmacology
Background:
- Exercising horses exhibit elevated right and left atrial pressures.
- Ventricular relaxation limitations may contribute to these high pressures.
Purpose of the Study:
- To investigate right ventricular (RV) myocardial relaxation characteristics during exercise in horses.
- To determine the impact of frusemide on RV relaxation and atrial pressures during exercise.
Main Methods:
- Horses underwent exercise tests at various speeds (8-14 m/s) 4 hours post-frusemide administration.
- Right ventricular pressure was analyzed using Fast Fourier Transform techniques.
- Parameters including RV relaxation time constant (tau) and pressure change rates (+dP/dtmax, -dP/dtmax) were measured.
Main Results:
- Frusemide significantly attenuated mean right atrial (RA) pressure at all exercise speeds.
- RV relaxation parameters (tau, delta 65-20) generally decreased with exercise, indicating improved relaxation.
- Frusemide did not significantly alter most RV relaxation parameters, except for a prolonged RV tau at 12 m/s. Stroke volume was reduced by frusemide at several speeds.
Conclusions:
- Frusemide's reduction of high atrial pressures in exercising horses is not mediated by significant alterations in ventricular relaxation rate.
- The study provides insights into cardiovascular adaptations during equine exercise and the effects of diuretic intervention.
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