The influence of cilazapril on indices of autonomic function in normotensives and hypertensives.

Abstract

1. In two single dose studies, acute blood pressure reduction with cilazapril was not associated with any significant change in supine or erect heart rate in either normotensives or hypertensives. 2. To investigate the lack of reflex cardioacceleration, a series of autonomic function tests was undertaken when there was maximum ACE inhibition, maximum evidence of angiotensin II withdrawal and the lowest blood pressure. 3. There was no evidence that cilazapril had any significant impact on indices of sympathetic nervous activity or the integrity of baroreflex mechanisms. 4. The results for the bradycardic response to apnoeic facial immersion, suggested enhanced parasympathetic activity, consistent with the withdrawal of the vagolytic actions of angiotensin II. 5. These results suggest that the absence of a heart rate response to ACE inhibition is not related to a profound sympatho-inhibitory effect or an impairment of baroreflex function. While there is some evidence of enhanced cardiac parasympathetic tone it seems unlikely that this is the sole explanation for the lack of cardioacceleration.