Author:

Keywords:

Administration, Oral, Adult, Angiotensin-Converting Enzyme Inhibitors, Antihypertensive Agents, Cross-Over Studies, Double-Blind Method, Enalapril, Humans, Hypertension, Losartan, Male, Middle Aged, Peptidyl-Dipeptidase A, Statistics, Nonparametric, T-Lymphocytes, Cytotoxic, Science & Technology, Life Sciences & Biomedicine, Cardiac & Cardiovascular Systems, Pharmacology & Pharmacy, Cardiovascular System & Cardiology, T lymphocytes, angiotensin-converting enzyme, enalapril, losartan, INHIBITION, INDUCTION, CAPTOPRIL, CELLS, EXPRESSION, 1102 Cardiorespiratory Medicine and Haematology, 1115 Pharmacology and Pharmaceutical Sciences, Cardiovascular System & Hematology, 3201 Cardiovascular medicine and haematology, 3214 Pharmacology and pharmaceutical sciences

Abstract:

This study evaluated the long-term effects of the angiotensin-converting enzyme inhibitor enalapril and the angiotensin II type 1 receptor antagonist losartan on the angiotensin-converting enzyme activity in T lymphocytes and plasma in patients with essential hypertension. The study was a randomized, placebo-controlled, double-blind, crossover design. Nine patients with sitting blood pressure > or = 95 mm Hg and < or = 105 mm Hg at the end of a 4-week placebo run-in period entered the double-blind phase of the study, which consisted of three 6-week periods during which patients were treated with placebo, enalapril (20 mg, once daily), or losartan (50 mg, once daily) The angiotensin-converting enzyme activity in T lymphocytes was measured as the activity of the degradation of the substrate Hippuryl-His-Leu and as the appearance of the dipeptide His-Leu, which was quantified spectrofluorometrically. Enalapril but not losartan suppressed (p < or = 0.01) the angiotensin-converting enzyme activity in plasma, whereas it stimulated (p < or = 0.05) the angiotensin-converting enzyme activity in circulating T lymphocytes. Our data document induction of angiotensin-converting enzyme in human T lymphocytes during long-term treatment with the angiotensin-converting enzyme inhibitor enalapril. Angiotensin II receptor type 1 antagonism with losartan had no effect on plasma or lymphocytic angiotensin-converting enzyme.