Loci of catabolism of beta-very low density lipoprotein in vivo delineated with a residualizing label, SVI-dilactitol tyramine
beta-Very low density lipoprotein (beta-VLDL) may be a major atherogenic lipoprotein, and knowledge of the sites of its catabolism should facilitate elucidation of mechanisms important in the regulation of its plasma concentrations. In this study, catabolic sites of beta-VLDL have been delineated in normolipidemic rabbits with a novel, radioiodinated, residualizing label, SVI-dilactitol tyramine ( SVI-DLT). Comparative studies of beta-VLDL and low density lipoprotein catabolism were performed with SVI-DLT conjugated to each lipoprotein and with lipoproteins iodine-labeled conventionally. Conjugation did not alter size distributions or charge characteristics of lipoprotein particles. The overall processing (binding and degradation) of lipoproteins by cultured rabbit skin fibroblasts was not influenced by SVI-DLT derivatization, suggesting that attachment of the label did not influence cell receptor-lipoprotein interactions. Furthermore, although degradation products of SVI-lipoproteins leaked out of the cells and into the medium, the degradation products of SVI-DLT lipoproteins were retained by the cells. The principal catabolic site of beta-VLDL in normolipidemic rabbits was found to be the liver with 54 +/- 4% of injected SVI retained in this organ 24 h after injection of SVI-DLT-beta-VLDL. When catabolism was normalized to tissue weight, the liver and adrenals were found to be approximately equally active in the metabolism of beta-VLDL. In agreement with results of other studies with residualizing labels, the principal organ of catabolism of SVI-DLT-LDL in vivo was the liver. The adrenals were the most highly catabolizing organ when results were normalized for tissue weight.
- Research Organization:
- Washington Univ. School of Medicine, St. Louis, MO
- OSTI ID:
- 6085131
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 27
- Country of Publication:
- United States
- Language:
- English
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550501* - Metabolism- Tracer Techniques