Frusemide attenuates the exercise-induced rise in pulmonary capillary blood pressure in horses.

The research aims to investigate the effect of frusemide on exercise-induced high pulmonary capillary blood pressure in horses. The researchers found that frusemide significantly reduced the exercise-induced increase in pulmonary pressures, which might minimize the risk of exercise-induced pulmonary hemorrhage.

Experiment Setup

• The experiment involved studying the cardiovascular system of eight healthy horses at rest and during various speeds of exercise. The speeds were 8, 10, 12 and 14 meters per second, performed on a treadmill.
• The researchers used catheter-mounted micro-tip-manometers in this study. This device was used to record precise pressure readings at various sites in the cardiovascular system of the horses. The measurements were zeroed at the shoulder point of the horses for accuracy.

Procedure

• Measurements were obtained under two scenarios, when horses did not receive any medication (control) and when horses were given frusemide 4 hours before the exercise. A single dose of 250 mg of frusemide was administered intravenously.
• The data were also collected on a separate day without frusemide administration, ensuring the consistency of the results.

Results

• Without medication, the values for heart rate, right atrial pressure, pulmonary artery pressure, pulmonary artery wedge pressure, and pulmonary capillary pressure were recorded at various speeds, with the highest being at 14 m/s.
• However, after frusemide was administered, all these values were significantly lower at 14 m/s. There was a slight increase in the heart rate, but this was not significant.
• This indicated that frusemide effectively lowered the pulmonary pressures even during high levels of exercise.

Implications of the Study

• If exercise-induced pulmonary hemorrhage (EIPH) arises from the failure of pulmonary capillaries under stress, the use of frusemide could potentially reduce or limit the extent of EIPH.
• The significant decrease in pulmonary pressures suggests a reduction in the force exerted on the pulmonary capillaries, which in turn reduces the likelihood of EIPH.