A comparison of two methods to investigate the metabolism of human apolipoproteins A-I and and A-II.

• Main Authors: J Shepherd, C J Packard, A M Gotto, Jr, O D Taunton
• Format: Article
• Language: English
• Published: Elsevier 1978-07-01
• Series: Journal of Lipid Research
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520412994

Two methods are compared for measuring the kinetic parameters of apolipoprotein A-I and A-II metabolism in human plasma. In the first, high density lipoprotein apoproteins were radioiodinated in situ in the lipoprotein particle (endogenous apoprotein labeling) while in the second, individually labeled apolipoprotein A-I or A-II was incorporated into the particle by in vitro incubation (exogenous apoprotein labeling). The catabolic clearance rate of exogenously labeled apolipoprotein A-I was consistently faster than that of endogenous apolipoprotein A-I. Conversely, endogenously and exogenously labeled apolipoprotein A-II were catabolized at identical rates. The fractional plasma clearance rates of endogenous apolipoproteins A-I and A-II were the same.