Comparative microscopic and biochemical study of the uptake of fluorescent and 125I-labeled lipoproteins by skin fibroblasts, smooth muscle cells, and peritoneal macrophages in culture
Uptake of low density lipoprotein (LDL) and of acetyl LDL was compared in skin fibroblasts, smooth muscle cells, and peritoneal macrophages with the use of lipoproteins labeled with either /sup 125/I or the fluorescent probe 3,3'-dioctadecylindocarbocyanine (DiI). The uptake of DiI-labeled lipoproteins was assessed by quantitative spectrofluorometry and by fluorescence microscopy. The DiI was quantitatively retained by the cells, while the /sup 125/I-LDL was degraded and /sup 125/I-labeled degradation products were excreted from the cells. In smooth muscle cells and fibroblasts the uptake of LDL was virtually the same whether measured with the use of the DiI or /sup 125/I-label. The labeling of acetyl LDL with DiI enhanced its uptake in peritoneal macrophages by an average of 18%. With the DiI label, lipoprotein uptake could be determined after as little as 10 minutes of incubation at 37 C. The pattern of uptake of the DiI-labeled lipoproteins was consistent with binding to specific receptors, because no DiI could be detected in mutant cells without LDL receptors, and uptake was competitively inhibited by addition of excess unlabeled lipoprotein. When the DiI-labeled lipoproteins were removed from the medium, there was a 5-15% loss of DiI from all cell types studied over the first 24 hours.
- Research Organization:
- Wake Forest Univ., Winston-Salem, NC
- OSTI ID:
- 6138493
- Journal Information:
- Am. J. Pathol.; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques