The influence of angiotensin converting enzyme inhibitors on lipid peroxidation in sera and aorta of rabbits in diet-induced hypercholesterolemia.

In hypercholesterolemia increased lipid and lipoprotein peroxidation occurs. The renin-angiotensin system plays an important role in atherogenesis. Angiotensin II induces smooth muscle cells proliferation and stimulates oxidation of LDL particles and foam cell accumulation. Inhibition of ang II production leads to decrease in lipid peroxide production. The aim of this study was to assess the lipid peroxidation expressed as concentration of thiobarbituric acid reactive species (TBARS) in sera and aorta homogenates after administration of two doses of angiotensin-converting enzyme (ACE) inhibitors (captopril, enalapril and quinapril) in diet-induced hypercholesterolemia in rabbits. Sixty-four New Zealand rabbits were used. Animals were fed with standard fodder, special diet (1% cholesterol content) or special diet + tested ACEI. Two doses of ACE inhibitors were used: i), equivalent to applied to humans, ii), dose 10 times higher. The animals were divided into 8 groups: control, standard fodder; B, special diet; C1, C2, special diet + captopril in doses 2.5 and 25 mg/kg/24 h, respectively; E1, E2, special diet + enalapril in doses 0.75 and 7.5 mg/kg/24 h, respectively; Q1 and Q2, special diet + quinapril in doses 0.75 and 7.5 mg/kg per day, respectively. In cholesterol-fed rabbits and in groups receiving lower doses of tested ACE inhibitors, the serum TBARS concentration at 6 months was significantly higher in comparison to the control. The higher doses of enalapril, quinapril and captopril, prevented the cholesterol-induced rise in TBARS concentration. Lower dose of captopril attenuated the rise in TBARS concentration, it was significantly lower in comparison to group B, but higher than in the control group. In animals from groups B, E1, C1, Q1 TBARS concentration in aortae was significantly higher as compared to control group. Both doses of captopril and higher doses of enalapril and quinapril inhibited the rise of lipid peroxides concentration induced by cholesterol-rich diet.