High-density apolipoprotein A-I and A-II kinetics in relation to regional adiposity

High-density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I concentrations decrease with increasing central adiposity. The present study investigated possible mechanisms for these effects by examining the relationship between body mass index, regional adiposity, and HDL apo A-I and A-II metabolism. Fifteen sedentary men and 10 male endurance athletes aged 22 to 44 served as subjects. HDL apo A-I and A-II metabolism was examined using 125I-labeled autologous HDL. Chest and thigh skinfold thickness and the ratio of chest to thigh skinfold thickness were used as indices of regional adiposity. The relationship of adiposity to HDL metabolism was examined using correlational and multiple regression analysis. In both subject groups, the fractional catabolic rate of apo A-I and A-II increased with increasing chest skinfold thickness and chest to thigh skinfold ratio (.43 < r2 < .66). This effect was partially independent of triglyceride or HDL cholesterol concentrations. Apo A-I and A-II fractional catabolic rates increased with increasing body mass index only in the sedentary men. Concentrations and synthetic rates (mg.d-1.kg-1) of apo A-I and A-II were not consistently related to body mass index or regional adiposity. Peripheral adiposity assessed by thigh skinfold thickness was not correlated with any parameter of apo metabolism. We conclude that HDL apo A-I and A-II catabolism increases with increasing central adiposity.