On the lipoprotein abnormality in type III hyperlipoproteinemia

starch block electrophoresis from the very low density lipoproteins (VLDL) (St 20-400) of patients with type III hyperlipoproteinemia. One of these, a2-VLDL, had a content of lipid and protein and physical characteristics similar to VLDL from normal subjects or patients with other forms of hyperglyceridemia. The other species, 9-VLDL, contained more cholesterol and less triglycer-ide in relation to the protein, than normal VLDL. Only the apoprotein of low density lipoprotein was immuno-chemically detectable in the P-VLDL; the proteins in the a2-VLDL reacted with antisera specific for low density lipoprotein and high density lipoprotein. The electrophoretic mobility of P-VLDL was similar to that of low density lipoprotein and significantly less than that of a2-VLDL. Isolated P-VLDL had a lesser mean flotation rate than a2-VLDL, but both a2- and 8-VLDL were found throughout the Si 20-400 flotation range. The relative quantities of a2- and f-VLDL could be varied by changing the diet or by heparin administra-tion. Most of the VLDL from type III patients on a high carbohydrate diet was in the a2-VLDL form. Dur-ing fasting, caz-VLDL fell and P-VLDL increased be-coming the predominant species of VLDL. Heparin-induced acceleration of triglyceride clearance also in-creased p-VLDL and decreased a2-VLDL. These find-ings suggest a precursor-product relationship between the a2- and P-forms of VLDL