Co-incubation of native and oxidized low-density lipoproteins: potentiation of relaxation impairment.
The influence of native low-density lipoprotein (LDL) on the inhibition of endothelium-dependent relaxation previously induced by oxidized LDL was investigated with intact rabbit aortic rings. We also tried to assess oxysterol involvement in the native lipoprotein effects. Lipoprotein fractions (1 mg protein/ml) were tested for their ability to inhibit the vasorelaxation induced by acetylcholine in aorta rings previously precontracted by noradrenaline vs. that in control strips in Krebs buffer. Co-incubation of oxidized and native LDL reinforced the oxidized LDL-induced inhibition, compared to the impairment evoked by oxidized LDL alone (E(max)=43.3+/-6.7% and 61. 4+/-5.4%, respectively; P<0.05). Finally, smaller amounts of 7-oxy-cholesterols were recovered in organ baths after co-incubation of native and oxidized LDL than after incubation of oxidized LDL alone. Conversely, more oxy-cholesterols were found in the strip vessels under the same conditions (% of oxysterol incorporation: 0. 05158 vs. 0.10199, r=0.703). Together these results suggest that the strengthening of oxidized LDL-induced inhibition by native LDL is dependent on an oxysterol effect on arterial wall cells. Mechanisms involved in this phenomenon remain to be investigated.
Perségol
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L
Unité INSERM U498, Métabolisme des Lipoprotéines Humaines et Interactions Vasculaires, Faculté de Médecine, Boulevard Jeanne d'Arc, BP 87900, 21079 Cedex, Dijon, France. persegol@alcyone.u-bourgogne.fr
Sementa
V
V
Athias
A
A
Lecerf
J
J
Lallemant
C
C
Gambert
P
P
D000818:Animals; D001011:Aorta / Q000187:drug effects; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D007653:Ketocholesterols / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008297:Male; D011817:Rabbits; D014664:Vasodilation / Q000187:drug effects*
D007653:Ketocholesterols; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; C003001:7-ketocholesterol