Relationship between Serum Lipids and Angiotensin Converting Enzyme Activity in Cholesterol-fed Rabbits

Abstract

Background Blockade of renin-angiotensin system reduces the development of atherosclerotic plaque in different animal models. In some experimental studies improvement of lipids metabolism was also observed after treatment with ACE-inhibitors. There is still little known about the mechanism of ACE-inhibitors action on lipids metabolism in hypercholesterolemic animals.
Methods The aim of the study was to assess the renin-angiotensin system activity in experimentally-induced hypercholesterolemia and the possible relationships between lipids parameters and ACE activity. Twenty male New-Zealand rabbits were divided into two groups with the following dietary conditions: standard diet (n = 10) and 1% cholesterol diet (n = 10). After six months of experiment the blood was collected for analysis of ACE activity and lipids. Total, LDL and HDL cholesterol, triglycerides, phospholipids and ACE activity was measured enzymatically.
Results At the end of the experiment there were no correlations between ACE activity and serum lipids in normolipidemic group. When compared with the control group, in cholesterol-fed rabbits ACE activity was increased (p < 0.05). We observed a positive correlation between ACE activity and serum triglycerides (r = 0.6%, p < 0.04) and inverse correlation between ACE activity and HDL cholesterol (r = -0.89, p < 0.001) in hypercholesterolemic rabbits. There was no correlation between ACE activity and any other lipids parameters in this group.
Conclusions We have shown that standard diet supplemented with 1% cholesterol leads to increased activation of ACE and that there is a correlation between this activity and triglycerides and HDL cholesterol metabolism. This may be in part responsible for the observed changes in lipids metabolism after ACE-inhibitors in hyperlipidemic animals and then be one of the antiatherosclerotic properties of ACE-inhibitors.