Two NO synthase (NOS) isoforms have been described in vessels, an endothelial constitutive NOS (eNOS) and an inducible NOS (iNOS). The purpose of the present study was to examine the endothelium-dependent and endothelium-independent hypotensive response in aging rats, analyzing the ability of their vessels to produce NO. The studies were performed in 2 groups of euvolemic, conscious, male Wistar rats: aging rats (n=20, 18 months old) and young rats (n=20, 5 months old). The hypotensive responses to acetylcholine, bradykinin, and sodium nitroprusside were determined. Furthermore, the expression of the NOS isoforms by Western blot and the eNOS and iNOS activities, defined as Ca2+-dependent and Ca2+-independent conversion of [14C]L-arginine into [14C]L-citrulline, respectively, were also determined. In the aging rats, we found an impaired hypotensive response to acetylcholine and bradykinin (2 NO- and endothelium-dependent hypotensive agents) that was accompanied by a preserved hypotensive response to sodium nitroprusside. Aging rats also demonstrated an enhanced sensitivity response to the pressor effect of the L-arginine antagonist L-Nomega-nitro-L-arginine and a reduced vasoconstrictor response to angiotensin II. The inhibition of NO synthesis normalized the pressor effect of angiotensin II in the aging animals. Nitrite plus nitrate plasma levels were increased in aging rats. Furthermore, cGMP content was also higher in the aging vessels. In the aging aortas, the expression of both eNOS and iNOS isoforms was enhanced. However, in aging rats, the activity of the eNOS isoform was markedly reduced, a finding that was accompanied by the presence of iNOS activity. The vessel wall of aging rats showed an enhanced expression of eNOS and iNOS isoforms. However, eNOS activity was reduced in the aging animals. These findings could explain the impaired endothelium-dependent hypotensive response associated with aging.

Changes in endothelial nitric oxide synthase (eNOS) expression may be involved in the endothelium-dependent vasorelaxation dysfunction associated with several vascular diseases. In the present work, we demonstrate that eNOS mRNA contains a previously undescribed cis element in the 3 untranslated region (3 UTR). A U؉C-rich segment in the 3 UTR is critical in complex formation with bovine aortic endothelial cell cytosolic proteins. Tumor necrosis factor alpha (TNF-␣), which destabilizes eNOS mRNA, increased the binding activity of the cytosolic proteins in a time-dependent manner. These data suggest that endothelial cytosolic proteins bind to the 3 UTR of eNOS mRNA. These proteins may play a role in TNF-␣-induced eNOS mRNA destabilization.Nitric oxide (NO) is a gas generated by the metabolic conversion of L-arginine into L-citrulline by the activity of NOsynthesizing enzymes (NO synthases [NOS]) (23). Two major types of NOS activities have been identified in the vessels: an endothelial isoform (eNOS), which is localized in the endothelium under physiological conditions, and an inducible isoenzyme, which requires cytokines or endotoxin activation for its expression (23,29). Loss of endothelium-derived NO results in vascular abnormalities including vasoconstriction, smooth muscle cell proliferation, and adhesion of blood elements to the vessel walls (12,16,23,26

S ystemic lupus erythematosus (SLE) is a multisystemic chronic autoimmune inflammatory disorder that is associated with a high risk for the development of renal and cardiovascular disease, 1,2 which are major causes of mortality in these patients. 3 It predominantly affects young women of child-bearing age, the same population that is at lowest relative risk of atherosclerotic heart disease. In fact, women with lupus (age, 35-44 years) are >50 times as likely as healthy women without lupus to have a myocardial infarction. 4 Indeed, SLE is characterized by a high incidence of hypertension, 5-7 a wellestablished risk factor for the development and acceleration of atherosclerosis and ischemic heart disease. Oxidative stress and the inactivation of nitric oxide (NO) by vascular superoxide anion (O 2 ·− ) play a critical role in the pathogenesis of endothelial dysfunction, an early event in most cardiovascular diseases, including hypertension. 8,9 Reactive oxygen species (ROS) have been considered as risk and enhancer factors for autoimmune diseases, 10 and oxidation is one of the major factors responsible for atheroma development in this context. Indeed, SLE is a disease characterized by an increased oxidative damage.11-14 Free radical-mediated reactions are implicated in endothelial dysfunction in SLE, 15 and renal oxidative stress plays an important mechanistic role in the development of autoimmune-mediated hypertension. 16Abstract-Hydroxychloroquine has been shown to be efficacious in the treatment of autoimmune diseases, including systemic lupus erythematosus. Hydroxychloroquine-treated lupus patients showed a lower incidence of thromboembolic disease. Endothelial dysfunction, the earliest indicator of the development of cardiovascular disease, is present in lupus.Whether hydroxychloroquine improves endothelial function in lupus is not clear. The aim of this study was to analyze the effects of hydroxychloroquine on hypertension, endothelial dysfunction, and renal injury in a female mouse model of lupus. NZBWF1 (lupus) and NZW/LacJ (control) mice were treated with hydroxychloroquine 10 mg/kg per day by oral gavage, or with tempol and apocynin in the drinking water, for 5 weeks. Hydroxychloroquine treatment did not alter lupus disease activity (assessed by plasma double-stranded DNA autoantibodies) but prevented hypertension, cardiac and renal hypertrophy, proteinuria, and renal injury in lupus mice. Aortae from lupus mice showed reduced endotheliumdependent vasodilator responses to acetylcholine and enhanced contraction to phenylephrine, which were normalized by hydroxychloroquine or antioxidant treatments. No differences among all experimental groups were found in both the relaxant responses to acetylcholine and the contractile responses to phenylephrine in rings incubated with the nitric oxide synthase inhibitor N G -nitro-l-arginine methyl ester. Vascular reactive oxygen species content and mRNA levels of nicotinamide adenine dinucleotide phosphate oxidase subunits NOX-1 and p47 phox were increased in lupus...