Effect of amlodipine on blood and aortic tissue concentration of endothelin in male rabbits receiving atherogenic diet

Background: Different factors are involved in the induction and progress of atherosclerosis. One of these factors is endothelin-1. Since, in atherosclerotic vessels, there are certain obvious changes, with abnormality in the transfer of calcium ions, some researchers have suggested that calcium channel blockers can slow down the process of atherosclerosis. In this study, we evaluated the effects of amlodipine and/or a high cholesterol diet on the blood and aortic concentration of endothelin in rabbits.
Materials and Methods: Thirty-six male New Zealand white rabbits were divided into four groups: the normal control group, normal diet plus amlodipine group, high-cholesterol diet group, and high-cholesterol diet plus amlodipine group. After 8 weeks all animals were anesthetized and blood or tissue samples were collected.
Results and Conclusions: Eight weeks of amlodipine treatment significantly reduced total cholesterol, low density lipoproteins (LDL), and triglycerides (TG) in the hypercholesterolemic diet group. Although amlodipine treatment tended to enhance HDL/LDL and HDL/cholesterol ratios in the mentioned group, these effects were not statistically significant. The observed significant increase in plasma high density lipoprotein cholesterol (HDL-C) and decrease in TG is considered to be the main effect of amlodipine treatment on the serum lipid profile in the control group. The plasma level of endothelin-1 in the atherosclerotic model group was significantly increased as compared to the control group ( P < 0.01). After treatment with amlodipine, the ET-1 level reduced significantly in the control and high-cholesterol diet rabbits ( P < 0.01). A high-cholesterol diet induced atherosclerotic lesions and thickening of the intima in the thoracic aorta. Amlodipine consumption reduced atherotic injuries in high-cholesterol diet rabbits. There were no lesions in the normal diet groups or the normal diet with amlodipine group. High cholesterol causes increase in plasma and tissue endothelin. Amlodipine treatment reduced the levels of total cholesterol, LDL, and TG and, in a high lipid intake situation reduced endothelin levels in plasma and aortic tissue. Our data shows that amlodipine treatment may be considered as one of the important interventions for prevention and regression of atherosclerosis.