Background and Aim: Nitric oxide (NO) is a substance which protects vessels against atherogenic effects. Previous studies have shown that there is a direct relationship between increasing of permeability of endothelial cells and formation and progression of atherosclerosis. The aim of this study was to evaluate the role of L-Arginine in permeability of aortic endothelial cells and serum lipoprotein level in high-cholesterol fed rats.

  Materials and Methods: In this experimental study, 36 male rats were divided into two groups one with a normal and the other with a high-cholesterol diet .Then each group was divided into two sub-groups :Group “a” used L-Arginine 2.25% in water and group”b” used safe drinking water. After eight weeks, the right carotids of the animals were cannulated and 20 mg/kg of Evans Blue was injected into the subjects. Then, the whole aorta of each animal was dissected and put in 2.5ml formamid solution. After 24 hs, absorbance of the solution was measured by means of spectophotometer. Finally, the obtained data was analysed by SPSS software using one-way ANOVA, and Tukey statistical test and P≤0.05 was taken as the significant level.

  Results: L-Arginine decreased endothelial permeability in aorta in rats feeding on high-cholesterol foods in comparison with the control group. (P<0.005). In addition, L-Arginine reduced the LDL level in the blood serum of rats with a high-cholesterol diet in comparison with the control group (P<0.005).

  Conclusion: Administration of L-Arginine has a protective effect on the permeability of endothelium of aortic vessels in hypercholesterolemic condition.