Removal of Chylomicron Remnants from the Bloodstream is Delayed in Aged Subjects

Figures

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  Figure 1.. Kinetic model employed for chylomicron-like emulsion metabolism in vivo The observed data (compartments C1 and C2) present a biexponential curve. Compartments C1- C4 represent kinetics of 14C-cholesteryl oleate (14C-CE). Compartments C5 - C8 represent kinetics of 3H-triglycerides (3H-TG). Compartments C1 and C5 represent emulsion after plasma injection. Compartments C2 and C6 represent emulsion after redistribution. Compartments C3 and C7 correspond extra-vascular space, mainly the liver, and C4 and C8 the emulsion labeled lipids recirculation. The constants ki,j (min-1) represent the fractional catabolic rate (FCR) or transfer from compartment j to compartment i over time. k3,1 and k7,5 - fraction of injected emulsion that is removed directly from plasma by the liver and other tissues. k2,1 and k6,5 - emulsion transfer rates to a complex plasma lipoprotein pool. k3,2 and k7,6 - removal from the plasma of the emulsion mainly by the liver. k4,3 and k 8,7 - emulsion transfer rates to VLDL (labeled lipids recirculation). k3,4 and k7,8 - recirculated lipids removal by the liver. k0,4 and k0,8 - output of labeled lipids from the body.

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  Figure 2.. Plasma decay curve of the emulsion cholesteryl esters (A) and triglycerides (B) in healthy subjects with age under 30 years (young) and those with age above 60 years (older). The chylomicron-like emulsion labeled with the radioactive lipids was injected intravenously after a 12 hour fast. Plasma samples were taken at regular intervals over 60 minutes to determine the radioactivity remaining in the plasma in a scintillation solution.