Lecithin: Cholesterol Acyl Transfer Rate in Plasma and its Relations to Lipoprotein Concentrations and to Kinetics of Bile Acids and Triglycerides in Hyperlipoproteinemic Subjects

Abstract

The lecithin:cholesterol acyl transfer (LCAT) rate and the concentrations of lipids and lipoproteins in plasma were determined in 85 normolipidemic reference subjects and in 89 subjects with different types of hyperlipoproteinemia (38 type 11a, 9 type lib. 2 type III. 38 type IV and 2 type V). The mean molar LCAT rate was lower in the reference group than in all types of hyperlipoproteinemia. The type IV and type V subjects had the highest molar LCAT rates. The mean fractional LCAT rate was reduced in type Ha and elevated in type IV compared to the reference group. In the hyperlipoproteinemic subjects the molar LCAT rate correlated positively with the triglyceride (TG)or the very low density lipoprotein (VLDL) concentration in plasma and with the body weight. The fractional LC AT rate correlated negatively with the LDL-total cholesterol (TC) concentration in plasma. After two months on a weight-reducing diet the mean molar and fractional LCAT rates were reduced by 17% and 6% respectively in 39 hypertriglyceridemic subjects. The changes of the molar LCAT rate correlated positively with the changes of the TG. unesterified cholesterol, and phospholipid concentrations in plasma and with the changes of the body weight. The changes of the fractional LCAT rate correlated negatively with the changes of the LDL-TC concentration in plasma. The production rate of bile acids and the turnover of endogenous TG, which were determined in 7 type IV subjects, correlated positively with the molar LCAT rate. There was no correlation between the bile acid production and the molar LCAT rate in 12 type Ila subjects. The results indicate that there are close relations between the production rate of cholesteryl esters (CE)in plasma and the production rate of VLDL and bile acids in type IV subjects. It is suggested that the molar LCAT rate determined in vitro might reflect the turnover of CE in plasma in vivo.

Key Words:

• lipids
• metabolism
• obesity
• phospholipids