Incubation of endothelial cells in a superoxide-generating system: impaired low-density lipoprotein receptor-mediated endocytosis.
Endothelial cells (EC) of blood vessels are submitted to oxidative stress under various circumstances. These conditions may modify EC functions; therefore, in the present work we have studied the receptor-mediated endocytosis of low-density lipoproteins (LDL) and malondialdehyde-modified LDL by the LDL receptor and the "scavenger" receptor, respectively, in cultured human umbilical vein EC after short (0-120 minutes) incubations in a superoxide anion (O2-) generating system. In both receptor-mediated processes, the oxidative stress produces a significant decrease at four different LDL concentrations (5-50 micrograms/ml) after 120 minutes of oxidation. On the other hand, the fluid-phase endocytosis of sucrose by EC seems to be stimulated by these conditions. Furthermore, incorporation of antioxidant enzymes in the O2- -producing system shows that H2O2 is an obligatory intermediate in order to produce the effect on the receptor-mediated processes. Hypotheses concerning the mechanisms involved in the modifications of endocytotic processes and their implications in vivo are discussed.
Poumay
Y
Y
Unité de Cytologie, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
Ronveaux-Dupal
M F
MF
D004705:Endocytosis; D004727:Endothelium / Q000166:cytology*; D006801:Humans; D008315:Malondialdehyde / Q000378:metabolism; D010873:Pinocytosis; D011973:Receptors, LDL / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D013997:Time Factors; D014969:Xanthine Oxidase / Q000378:metabolism
D011973:Receptors, LDL; D013481:Superoxides; D008315:Malondialdehyde; D013395:Sucrose; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase