In vivo gene transfer of endothelial nitric oxide synthase to carotid arteries from hypercholesterolemic rabbits enhances endothelium-dependent relaxations

Background and Purpose-Hypercholesterolemia is associated with abnormal end othelium-dependent vasorelaxation due to decreased nitric oxide bioavailabi lity. Our aim was to examine the effect of adenovirus-mediated gene transfe r of endothelial nitric oxide synthase (eNOS) to the hypercholesterolemic r abbit carotid artery In vivo. In addition, we examined whether adenovirus-m ediated gene transfer was associated with vascular dysfunction. Methods-Rabbits were fed a 1% cholesterol diet for 4 weeks followed by a 0. 5% cholesterol diet for 6 weeks. Vascular reactivity was assessed in nontra nsduced carotid arteries from chow- and cholesterol-fed animals. In additio n, carotid arteries were surgically isolated, and 2 separate doses of adeno viral vectors encoding eNOS or beta-galactosidase (Ad beta Gal) on the cont ralateral side were delivered to the lumen (1x10(10) and 5x10(10) pfu/mL). Results-Abnormal acetylcholine-mediated endothelium-dependent vasorelaxatio n was detected in the carotid artery from cholesterol-fed animals, whereas responses to calcium ionophore A23187 and diethylamine NONOate were normal. Vascular reactivity was similar in nontransduced and Ad beta Gal-transduce d hypercholesterolemic vessels, In vessels transduced with eNOS, transgene expression was demonstrated by immunostaining in both the endothelium and t he adventitia and by Western blot analysis. High-dose but not low-dose eNOS gene transfer enhanced endothelium-dependent relaxation in vessels hom cho lesterol-fed rabbits. Conclusions-Adenovirus-mediated gene transfer of eNOS to carotid arteries o f cholesterol-fed animals improves endothelium-dependent relaxation when an optimal viral titer is administered.