title: Effects of 7-ketocholesterol on the activity of endothelial poly(ADP-ribose) polymerase and on endothelium-dependent relaxant function.
abstract: Oxidative and nitrosative stress play an important role in the development of endothelial vascular dysfunction during early atherosclerosis. Oxidative stress activates the nuclear enzyme poly(ADP-ribose) polymerase (PARP) in endothelial cells. In patients with atherosclerosis the level of oxidized LDL in the plasma is elevated. In oxidized LDL various oxysterols have been identified, such as 7-ketocholesterol (7K). 7K has been shown to induce PARP activation in microglial cells. The aim of the current study was to clarify the effects of 7K on the activity of endothelial PARP and on the endothelium-dependent relaxant function of blood vessels. We treated human umbilical vein endothelial (HUVEC) cells with 2-16 microg/ml 7K as well as vascular rings harvested from BALB/c mouse thoracic aorta with 90 microg/ml 7K for 2 h. A group of mice was treated with 7K subcutaneously for 1 week (10 mg/kg/day). We also conducted in vitro and in vivo experiments using pretreatment with buthionine sulphoximine (BSO), a glutathione-lowering agent. The activity of PARP was calculated by measurement of tritiated NAD incorporation. The activity of PARP increased significantly in 7K-treated HUVEC cells. After BSO pretreatment, this increase was higher. Isolated vascular rings demonstrated no change in endothelium-dependent relaxant function after 2 h of incubation with 7K, even after BSO pretreatment. In vivo treatment with 7K for 1 week had no effect on the relaxant function. Our experimental results suggest that although 7-ketocholesterol can activate PARP enzyme in endothelial cells, it is not sufficient on its own to cause impairment in the endothelium-dependent vascular reactivity.
authors.affiliation: Department of Human Physiology and Clinical Experimental Research, Semmelweis University, Budapest 1082, Hungary.
authors.forename: Levente
authors.initials: L
authors.lastname: Kiss
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Domokos
authors.initials: D
authors.lastname: Gero
authors.forename: Katalin
authors.initials: K
authors.lastname: Módis
authors.forename: Zsombor
authors.initials: Z
authors.lastname: Lacza
authors.forename: Csaba
authors.initials: C
authors.lastname: Szabó
mesh_terms: D018929:Cell Culture Techniques; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007150:Immunohistochemistry; D007653:Ketocholesterols / Q000494:pharmacology*; D009126:Muscle Relaxation / Q000187:drug effects*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D004791:Enzyme Inhibitors; D007653:Ketocholesterols; D011065:Poly(ADP-ribose) Polymerases; C003001:7-ketocholesterol