EFFECTS OF ETHYL ALL-CIS-5,8,11,14,17-ICOSAPENTAENOATE ON THE PHYSICAL-PROPERTIES OF ARTERIAL-WALLS IN HIGH CHOLESTEROL DIET-FED RABBITS

The effects of ethyl all-cis-5,8,11,14,17-icosapentaenoate (EPA-E) on in vivo physical properties of arteriosclerotic aorta and femoral arte ry in high cholesterol diet (HCD)-fed rabbits were studied. The aortic pulse wave velocity (PWV) of rabbits fed HCD for 12 weeks (control gr oup) tended to be higher than that of rabbits fed a normal diet (norma l group). Because the PWVs in HCD-fed rabbits administered orally with 30 and 300 mg/kg/day EPA-E were significantly lower than the PWV of t he control group, the distensibility of arteriosclerotic aorta was imp roved with administration of EPA-E. The stiffness parameter (beta) val ue as an in vivo indicator of arteriosclerosis was significantly highe r in the control group than in the normal group and improved with admi nistration of EPA-E to almost the same level as that of the normal gro up. The beta-values were in significant negative correlation with medi al elastin content and medial smooth muscle cell (SMC) density in thor acic aorta and in positive correlation with the free cholesterol conte nt in abdominal aortic SMC. On the other hand, they were not correlate d with either the cross-sectional area of intimal thickening lesions o r the plasma lipid levels measured simultaneously. The femoral PWVs we re, like those in the aorta, higher in the control group as compared w ith the normal group, and the changes were improved with administratio n of EPA-E. These results show that EPA-E improved the in vivo distens ibility of arteriosclerotic arteries in HCD-fed rabbits. The mechanism of this improvement with EPA-E appeared to be related to histologic a melioration in the aortic medial elastic fibers and SMC and to protect ion from free cholesterol accumulation in SMC as one of the probable c auses.