Plasma high density lipoprotein subgroup distribution in rats fed diets with varying amounts of sucrose and sunflower oil

Abstract

Abstract The effect of varying the dietary sunflower oil/sucrose (SO/SU) ratio on rat plasma lipid concentration and lipoprotein distribution was studied. Four groups of 10 rats were fed for 4 weeks diets with varying SO/SU ratios. Lipoprotein components were then estimated in whole plasma and after cumulative density ultracentrifugation. Whole plasma triacylglycerol (TG), total cholesterol (TC) and free cholesterol (FC) decreased with increasing SO/SU ratio; the CE/FC ratio increased, because CE remained virtually unaltered. Plasma TG‐lowering was due to a decrease in VLDL and LDL‐TG. Protein, CE and FC in d=1.063–1.100 g/ml (HDL 2b ) and d=1.100–1.125 g/ml (HDL 2a ) lipoproteins decreased upon increasing the SO/SU ratio. In contrast, in d=1.125–1.200 g/ml (HDL 3 ) lipoproteins, there was a concomitant increase in these components. Although increasing the SO/SU ratio effected more protein and CE transportation in HDL 3 and less in HDL 2 , the total amount of these components in high density lipoproteins (d=1.063–1.200 g/ml) remained constant. Apo A‐I and apo C‐III decreased in HDL 2 but increased in HDL 3 upon increasing the SO/SU ratio. Also, HDL 2 apo E, and the apo C‐II/apo C‐III and small apo B/large apo B ratios in VLDL and LDL were lowered by increasing the SO/SU ratio. The hepatic VLDL‐TG output during isolated liver perfusion was lowest in rats fed the diet with the highest SO/SU ratio. In perfusate, like in plasma, the VLDL and LDL apo C‐II/apo C‐III ratio, as well as the small apo B/large apo B ratio, decreased upon increasing the dietary SO/SU ratio. The results indicate that there can be appreciable diet‐dependent variations in plasma HDL subgroup distribution in spite of unchanged total HDL levels.