The relevance of glycosaminoglycan sulfates to Apo E induced lipid uptake by hepatocyte monolayers.

The binding of Apolipoprotein E supplemented triglyceride emulsions to sulfated glycosaminoglycans demonstrated specificity for the carbohydrate polymers. Glucosamine containing glycosaminoglycans with relatively less sulfate had little affinity for the Apo E emulsion whereas those with more sulfate (i.e.

Hepatic uptake of chylomicrons and triglyceride emulsions in rats fed diets of differing fat content.

The hepatic removal of plasma chylomicrons was determined for rats fed the following diets: a) containing no triglyceride, b) regular chow diet with 4.5% of its mass as lipid and, c) a corn oil-supplemented chow with triglyceride accounting for 20% of the mass. The fractional hepatic uptake of either radiolabeled chylomicrons or a triglyceride emulsion was reciprocally related to the amount of lipid in the diet.

Differing uptake of emulsion triglyceride by the fed and fasted rat liver.

The recycling perfusion of a fasted rat liver with an apoprotein E-enriched synthetic triglyceride emulsion revealed a significantly greater hepatic uptake of both the apoprotein and the triglyceride than did the liver of a chow-fed animal. This greater hepatic triglyceride uptake by the perfused fasted liver in comparison to the fed was also noted for emulsions containing no added apoprotein or supplemented with both the E and CIII-1 proteins. However, no difference in the uptake of the triglyceride emulsion was seen for the fed and fasted livers when evaluated by a nonrecycling single pass perfusion.

Effect of apolipoproteins on the induction of hepatic steatosis in rats.

The incorporation of apolipoprotein E isolated from human very low density lipoproteins on a triglyceride emulsion produced a substantial increment in hepatic triglyceride after 1 h of in vitro perfusion through the isolated liver of a fasted rat. Both gross and microscopic morphology confirmed a substantial steatosis. Perfusions with triglyceride emulsions which contained no apoipoproteins resulted in a modest increment in hepatic triglyceride although considerably less than emulsions with the E protein, and no morphologic features of steatosis.

The uptake of high density lipoprotein cholesteryl ester in the perfused rat liver.

The hepatic uptake of high density lipoprotein cholesteryl ester was determine in a nonrecycling isolated rat liver perfusion. High density lipoprotein rich in the E apoprotein (apoE) showed about 10 times more uptake of the ester on a single pass than the bulk of the high density lipoproteins rich in the A-I protein. The apoportein recoveries in the liver paralleled the ester for both lipoproteins.