Abstract
Plasma lecithin: cholesterol acyltransferase (LCAT) were studied for their activity and fatty acid specificity (an index of the nature of fatty acid esterified)in vitro with the male rat fed glucose or sucrose as a sole source of carbohydrate.
Administration of sucrose for 14 days resulted in the elevation of the triglyceride level and tended to increase phospholipid in plasma. The LCAT activity was decreased by sucrose feeding. It was suggested that the decrease was attributable mainly to the decreased level of the enzymatic activity in plasma, but the effect of the changes of a substrate, lipoproteins, could not be excluded. Fatty acid specificity of LCAT was changed by sucrose feeding: relative formation of the cholesterol oleate was increased. The change was dependent on the change in the properties of the substrate, but not on that of the nature of the enzyme.
In experiment of refeeding commercial pellet, glucose or sucrose diets for 2 days after fasting for 2 days, the activity was not different between rats refed glucose or sucrose. However rats refed these sugars exhibited the lower activity and produced the larger proportion of the oleate ester than those refed a pellet ration. These changes appeared to be attributable to the influences of the diets on the substrate and the enzyme.
There was a correlation between the concentration of triglyceride in plasma and the activity of LCAT, suggesting a probable role of LCAT in the plasma triglyceride metabolism.
These results indicate that the LCAT reaction in rat plasma is influenced in a different manner not only by the difference in the dietary sugars, but also by the difference in the prefeeding habit of plasma donors, feeding or refeeding after fasting.
