Modulation of acute transient exercise-induced hypertension after oral administration of four angiotensin-converting enzyme inhibitors in normotensive horses.

The research examines the influence of angiotensin-converting enzyme inhibitors (ACEIs) on the changes in the blood pressure of healthy, normotensive (normal blood pressure) horses during acute transient exercise-induced hypertension. Results suggest that using oral Benazepril could mitigate exercise-induced hypertension in horses.

Study Design and Methodology

• The research involved six healthy horses. Each horse underwent five trials where they accomplished a treadmill exercise of 8m/s for 1 minute.
• The trials occurred two hours after the horses received oral administration of a placebo or one of the four angiotensin-converting enzyme inhibitors namely: Enalapril, Quinapril, Ramipril, and Benazepril.
• Key measurements taken during the trial include serum angiotensin-converting enzyme (ACE) activity, and systolic (SBP) and diastolic (DBP) blood pressures. These were recorded at rest, two hours after the administration, and within the first 20 seconds after exercise.

Findings

• The researchers observed that the maximum average serum ACE inhibition two hours after oral administration was lowest with the placebo at 4.8%, and highest with Benazepril at 71.68%.
• There were no significant differences in the serum ACE inhibition between Enalapril and Quinapril.
• Similarly, there were no differences observed in the SBP and DBP resting times and pre-exercise, across all five trials.
• However, the SBP and DBP increased in response to exercise. The increases in SBP were: 67.6% with the placebo, 52.7% with Enalapril, 43.1% with Quinapril, 26.6% with Ramipril, and just 4.2% with Benazepril. The DBP also increased post exercise: 20.6% with placebo, 13.2% with Enalapril, 11.7% with Quinapril, 16.6% with Ramipril, and 3.7% with Benazepril.

Conclusion

• The researchers concluded that oral Benazepril administration, amounting to 0.5mg/kg dosage, controlled the physiological hypertension prompted by exercise in horses that were normally normotensive. However, changes in serum ACE activity during exercise did not reach statistical significance.