Effect of enalapril (Reniteс) on the renin-angiotensin-aldosterone and sympathoadrenal system in hypertensive patients

Objective. To study the infl uence of enalapril 20 mg/day on the sympathoadrenal (SAS) and renin-angiotensinaldosterone systems (RAAS). Design and methods. 149 subjects (102 patients with essential arterial hypertension (EAH) and 47 patients with primary hyperaldosteronism, PHA) were included. Mean systolic blood pressure (BP) (M  m) was 194,6  7,4 mmHg, diastolic BP - 116, 2  5,4 mmHg. Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were estimated by radio-immune method in active patients. PRA was rated as normal if ranged 1,0-3,0 ng/ml/h, PAC - 0,18-0,83 nmol/l (5-23 ng/dl or 50-230 pg/ml). Normal PAC/PRA ratio was 5-23. The daily urine excretion of adrenaline (normal - 18-33 mmol/l) and noradrenaline (normal - 150-256 mmol/l) were determined by fl uorometric method. Conclusions. 1) Effects of angiotensin-converting enzyme (ACE) inhibitors on the synthesis of aldosterone and catecholamines in EAH patients are associated with the changes of circulating angiotensin II concentration, and in PHA patients - with the decrease of tissue angiotensin II concentration in cortical layers of the adrenal gland and central nervous system. 2) Reactive increase PRA in EAH patients treated with enalapril is rather related to the blockade of renal tissue angiotensin-converting enzyme than to the circulating angiotensin II. 3) PHA patients are characterized by the phenomenon of up regulation of aldosterone receptors and of tissue renin-angiotensin system that is defi ned by optimum reduction of PAC, the lack of normalization of PRA and blood pressure in response to the application of enalapril 20 mg/day.