EDTA influences reactivity of isolated aorta from hypercholesterolemic rabbits

The effects of the trace metal chelator, ethylenediaminetetraacetic acid (EDTA), on endothelium-dependent reactivity of isolated aorta from normal and hypercholesterolemic rabbits were studied. Rings of abdominal aorta were mounted in organ chambers for measurement of isometric force and incubated in physiological salt solution with or without EDTA (26 microM). Aortic rings were obtained from rabbits fed a standard diet or a diet enriched with 0.5% cholesterol and 4% peanut oil for 10 wk. In rabbits fed the standard diet, endothelium-dependent relaxations to acetylcholine and A23187 were not significantly different in rings incubated in physiological salt solution with or without EDTA. In aortic rings from cholesterol-fed rabbits incubated in physiological salt solution with EDTA, the relaxations caused by either acetylcholine or A23187 were not significantly impaired compared with rings from rabbits fed a standard diet. Only in rings incubated in the absence of EDTA did hypercholesterolemia significantly inhibit endothelium-dependent relaxation compared with control rabbits. Relaxations to sodium nitroprusside were not different in rings incubated with or without EDTA in either group. Thus the effect of hypercholesterolemia on endothelium-dependent reactivity of rabbit aorta depends on the in vitro experimental conditions. This study emphasizes the importance of including a metal chelator in physiological solutions used in the in vitro study of blood vessels from hypercholesterolemic animals.