Effects of trandolapril on the sympathetic tone and reactivity in systemic hypertension

Hemodynamic and autonomic evaluations were carried out after 2-3 weeks of treatment with placebo and at the end of 4 weeks of treatment with an angiotensin converting enzyme (ACE) inhibitor, trandolapril, 2 mg/day in 18 hypertensive patients (average age, 48 +/- 2 years) of either sex. This treatment lowered the mean arterial pressure in the whole group from 112 to 105 mm Hg (p < 0.05) without significant changes in basal heart rate or norepinephrine (NE) and epinephrine plasma levels. Based on daytime ambulatory blood pressure monitoring, the patients were separated into 2 equal groups of 9 patients: the better responders (R), with an average decrease in mean arterial pressure of 12 mm Hg, and the lesser responders (NR), with an average fall of mean arterial pressure of 2 mm Hg. Before treatment, the R group had a higher resting heart rate, a lower cardiac output (-16%), and a higher peripheral resistance (+22%) than the NR group (difference not significant). Moreover, the R group was also observed to have a 33% higher plasma NE level (p < 0.05) in the supine position, associated with a 52% higher NE response to standing (p < 0.05), and a 40% lower number of beta-adrenergic receptors on lymphocytes, suggesting a higher sympathetic tone and reactivity in that group. Following treatment with the ACE inhibitor, heart rate and plasma NE levels were not altered significantly in either group, suggesting a blunting of the baroreflex response concomitant with the lowered blood pressure, especially in the R group.(ABSTRACT TRUNCATED AT 250 WORDS)