Cardiovascular effects of hydralazine HCl administration in horses.

The research study investigates the cardiovascular effects of hydralazine HCl, a vasodilator, on horses. The results suggest that it effectively dilates blood vessels, impacts heart rate and cardiac output without altering blood pressure, and has a moderate duration of action.

Study Design and Methodology

• The experiment was conducted on six standing awake adult horses.
• Measurements were taken for mean arterial, central venous, and pulmonary arterial blood pressures, thermodilution cardiac output, and pulmonary arterial blood temperature. These were used to calculate the total peripheral resistance.
• Baseline data was collected before administering a single dose of hydralazine HCl.
• Post-administration, the horses were observed for 420 minutes.

Observations and Findings

• The study uncovered that the mean arterial and central venous blood pressures remained unchanged compared to the baseline values after hydralazine administration.
• At the same time, it was found that heart rate and cardiac output increased from baseline measurements for about 260 minutes.
• The total peripheral resistance decreased for around 240 minutes, indicating a dilation of blood vessels.
• Additionally, a decrease in pulmonary arterial blood temperature was observed for 60 minutes after drug administration.
• Fluctuations were witnessed in mean pulmonary arterial pressure relative to the baseline during the study.

Conclusions

• The outcomes of the study suggest that intravenous administration of hydralazine HCl appears to be an effective vasodilator in horses.
• The drug appears to have a moderate duration of action, and while it does not change blood pressures, it impacts heart rate, cardiac output and blood temperature..