BACKGROUND: Many studies have suggested that angiotensin-converting enzyme inhibitors(ACEI) protect blood vessels through anti-atherosclerosis independent of lowering blood pressure, but its mechanism is still unclear.OBJECTIVE: To investigate the anti-atherosclerotic mechanism of ACEI by observing the effects of Enalapril on lipoprotein(a) and oxygen free radicals in patients with acute myocardial infarction (AMI) .DESIGN: A controlled study based on the observation of the patients with AMI.SETTING: Second Department of the South Building, General Hospital of Chinese PLAPARTICIPANTS: Thirty-five inpatients with AMI(19 males and 16 females, aged 42 -75 years old, and averaged (62 ± 9) years old and hospitalized at the Department of Cardiology of Tianjin Harbor Hospital from April 2001 to August 2002 were chosen. These patients were randomly divided into 2 groups: the therapeutic group(20 cases) and the control group(15cases). Inclusion criteria: the diagnosis of patients with AMI was confirmed by WHO criteria. Exclusion criteria: patients with renal dysfunction, shock,hypotension, a history of allergy to ACEI, and a history of severe cough induced by ACEI. All patients had not taken ACEI in the past 2 weeks and agreed to participate in this study.METHODS: On early morning of the third day after AMI, patients in the treatment group took 5 mg of Enalapril one time. If they had no first-dose reaction of hypotension, on the fourth day after AMI, the patients of the treatment group were given a dose of 5 mg twice per day for the following 2 weeks. Then, they were given the drug at a dose of 10 mg twice per day for 2 weeks. The patients in the control group were not given Enalapril. Blood samples were taken respectvely prior to the administration and 2 weeks and 4 weeks after the administration in the two groups. Serum content of lipoprotein(a), oxygen free radicals, triglyceride, total cholesterol, high density lipoprotein(HDL) cholesterol, Apo(a) were measured.MAIN OUTCOME MEASURES: We compared the level of serum of lipoprotein (a), oxygen free radicals (OFR), triglyceride, total cholesterol,HDL cholesterol, Apo(a) pre-treatment and post-treatment respectively in patients of the two groups.RESULTS: Serum levels of OFR were significantly lowered in the treatment group, which were(1 423.14±216.23), (1 076.62±287.12) and (566.57 ± 138.02) U/mL respectively 2 weeks and 4 weeks before and after the treatment(t =2. 937, 3. 571, P ＜0. 01), but there were no significant changes in serum concentrations of lipoprotein(a) and lipids( P ＞ 0.05) .CONCLUSION: Enalapril improved the prognosis of patients with AMI by antioxidation, but not by lowering the serum levels of lipoprotein(a) and lipids. The study can serve as a theoretical reference that the mechanism of Enalapril might inhibit atherosclerosis in patients with AMI.

0.05). Both Bosu and Enalapril could lower blood pressure remarkably (P