Selective impairment of blood pressure reduction by endothelial eNOS dimer-destabilization in mice

Endothelial dysfunction and oxidative stress are associated with hypertension but whether endothelial superoxide plays a role in the early development of essential hypertension remains uncertain. We investigated whether eNOS-derived endothelial oxidative stress is involved in the regulation of blood pressure. Wild-type eNOS (eNOS-Tg) or a novel dimer-destabilized eNOS-mutant harboring a partially disrupted zinc-finger (C101A-eNOS-Tg) was introduced in C57BL/6 in an endothelial-specific manner. C101A-eNOS-Tg showed significantly increased superoxide generation, protein- and eNOS-tyrosine-nitration, eNOS-S-glutathionylation, eNOS1176/79-phosphorylation and AMP-kinase (AMPKα) Thr172-phosphorylation in aorta, skeletal muscle, left ventricular myocardium and lung as compared to eNOS-Tg and wildtype (Wt)-controls. Exercise training increased phosphorylation of eNOS at Ser1176/79 and AMPKα in Wt while these physiologic adaptations were absent in C101A-eNOS-Tg. Aortic endothelium-dependent relaxation was similar in all studied strains. C101A-eNOS-Tg displayed normal blood pressure despite higher level of eNOS, while eNOS-Tg showed hypotension. Tempol completely reversed the occurring protein modifications and significantly reduced blood pressure in C101A-eNOS-Tg but not in Wt. Oxidative stress generated by endothelial-specific expression of genetically destabilized C101A-eNOS selectively prevents BP reducing activity of vascular eNOS, while having no effect on aortic endothelial-dependent relaxation. These data suggest that oxidative stress in microvascular endothelium may play a role for the development of essential hypertension.