Abstract
To elucidate the role of apolipoproteins in the evolution of hyperlipidemia, VLDL apolipoproteins E & C from human plasma, especially of the patients with alcoholic hypertriglyceridemia, was analyzed by isoelectric focusing.
VLDL prepared from fasting plasma by ultracentrifugation was delipidated with acetone-ethanol. Apo VLDL was applied on the 7.5% polyacrylamide gel containing 8M urea and 2% ampholite, and isoelectric focusing was done with 150V for 16 hours at 4°C, as described by Warnick, except that holizontal plate gel and the wider pH range (pH 3.5-pH 10.0) were adopted. After fixation, staining with Coomassie Brilliant Blue and destaining of the gels, relative proportions of apolipoproteins and their isoproteins were determined by densitometry at 580Å. In alcoholics, Apo E3/Apo E2 ratio in VLDL were lower than those of others and tended to decrease as their plasma triglyceride levels increased. Alcohol tolerance test resulted in inconsistant changes in the apolipoprotein or isoprotein destribution, partly because of the insufficiency of the amount of loaded alcohol. Apo E isoprotein patterns were examined in 42 cases. Among them, the incidence of “variant pattern” with apo E4 isoprotein was significantly higher in patients with alcoholic hypertriglyceridemia (type IV+type IIb) than in other hyperlipoproteinemics and normal controls.
Although the special function of apo E4 isoprotein has not been reported, it is suggested that the exsistence of apo E4 per se or the decrease of total apo E or the relative decrease of apo E3 may modify the lipoprotein metabolism and constitute one of the factors which facilitate hyperlipoproteinemia, triggered such as alcohol ingestion.
