A NOVEL METHOD FOR THE RAPID SEPARATION OF PLASMA-LIPOPROTEINS USING SELF-GENERATING GRADIENTS OF IODIXANOL

We describe a new method for the rapid fractionation of plasma lipopro teins, which makes use of a new non-ionic, iodinated, density gradient medium, iodixanol, commercially available as Optiprep(TM). The method is simple: plasma or serum is mixed with iodixanol followed by centri fugation in a vertical or near vertical rotor. Separation of VLDL, LDL and HDL can be achieved in 3 h and the lipoprotein fractions are comp arable in density and composition with those prepared using convention al salt based gradients. Each class of lipoprotein can be removed in a single fraction, or a profile of lipoprotein distribution can be obta ined using a gradient fractionator. Because the medium is inert, fract ions from the gradient can be analysed by agarose gel electrophoresis or assayed for lipid content or apolipoprotein composition by SDS-PAGE without removing the iodixanol. Small differences in electrophoretic mobility of HDL and LDL across several gradient fractions suggest that subfractionation of these classes may occur. The new method is simple , rapid and versatile with potential application for preparation of li poproteins and for analysis of lipoprotein profiles in the research or clinical laboratory.