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 steatosis induced in the in vitro perfused fasted livers by the emulsions with E protein could be prevented when CIII-1 apoprotein was also incorporated on the emulsion. A fed rat liver perfused with the E-enriched emulsion accumulated significantly less triglyceride than the fasted preparation. These data suggest that the apoprotein patterns of the plasma triglyceride-rich lipoproteins are of considerable importance for the partition of triglyceride between liver and plasma.