Comparison of uptake and degradation of low density lipoproteins by arteries and veins of rabbits.

The uptake and degradation of low density lipoproteins were compared in arteries and veins of rabbits in vivo. Rabbits were injected with low density lipoproteins labelled singly with 125I (125I-LDL) or doubly with 131I and with [125I]tyramine cellobiose (TC-LDL) which remains trapped intracellularly. After increasing times up to 24 h the largest vessels were perfused to remove blood, fixed in situ and excised. When the uptake of 125I-LDL by arteries and veins was compared on the basis of luminal surface area, there were no significant differences up to 3.5 h. When degradation rates of double labelled LDL were compared after 24 h on the same basis, the arteries contained significantly more TC label than the veins, but when the comparison was based on dry weights there were no significant differences. These results show that veins, like arteries, take up LDL from the circulating blood; and they suggest that the preferential accumulation of LDL in arteries susceptible to atherosclerosis may be accounted for, at least in part, by more degradation of LDL in arteries than in veins.