Dietary fatty acid composition influences the degree of human LDL oxidation, but has only minor effects on vascular tone in a bioassay system

Background and Aim: Oxidized LDL has been detected in atherosclerotic vesse ls and presumed to be one of the major rosk factors in atherosclerosis and cardiovascular diseases. The aims of the present study were to clarify whet her the oxidation degree of LDL influences arterial tone and whether differ ent long-lasting dietary habits have effects on biological vairables. Methods and Results: The lag of LDL oxidation was shorter (117 +/- 6 min) i n the fish diet group than in the vegetarian (153 +/- 5 min) or the control diet group (152 +/-0 10 min). The rat mesenteric arterial rings, which wer e preincubated with LDL oxidized t o1-30%, from the vegetarian and the fish diet groups dhowed (p<0.05) decreased NA-induced maximal contraction force s when compared to the control diet. The LDL oxidation degrees of 31-60% an d 61-90% had on effect on NA- and KCl-induced maximal contraction forces wh en compared t onative LDL, nor were there differences between the diet grou ps. Endothelium-dependent and independent relaxation responses behaved simi larly in all groups and were independent of the degree of oxidation. Conclusions: Dietary habits change the fatty acid composition of LDL, but h ave only minor effects on the vasoactive properties of oxidized LDL. (C) 20 00, Medikal Press.