Effects of high-dose alacepril on the renin-angiotensin-aldosterone system and autonomic nervous system function in healthy dogs

This study investigated the effects of low-dose and high-dose alacepril on the renin-angiotensin-aldosterone system (RAAS) and autonomic nervous system in healthy dogs. Six Beagle dogs received low-dose (2.0 mg/kg/day) or high-dose (6.0 mg/kg/day) alacepril for 4 weeks. Blood pressure, the urinary aldosterone-to-creatinine ratio (UAld: Cre), echocardiographic variables, and heart rate variability were assessed pre- and post-treatment. High-dose alacepril reduced blood pressure and left ventricular dimensions, indicating a reduced preload and afterload. Heart rate variability analysis showed an increased percentage of successive normal-to-normal interval differences of > 50 ms, suggesting enhanced parasympathetic activity despite detecting no changes in heart rate. UAld: Cre was not significantly different. Low-dose alacepril had no significant effect on any of these variables. In conclusion, high-dose alacepril demonstrates antihypertensive effects and enhances parasympathetic activity, which may confer cardiovascular benefits. It reduces blood pressure, decreases left ventricular preload, and increases parasympathetic activity. However, both high-dose and low-dose alacepril showed incomplete RAAS suppression. These findings highlight the need for further research to clarify its therapeutic potential in heart failure and hypertension.