The renin angiotensin aldosterone system is the dominant hormonal regulatory system controlling sodium balance and therefore blood pres- sure homeostasis. Abnormal modulation of this system is implicated in the pathogenesis of hypertension and end organ injury. We have previously developed the Cyp1a1-Ren2 transgenic rat to model an- giotensin II (ANG II) dependent hypertension. In this model hyper- tension causes renal injury, predominantly in the preglomerular vas- culature. The susceptibility to renal injury has a genetic component. A consomic/congenic study identified angiotensin converting enzyme (Ace) as an important modifer. However, renal injury is unlikely to be in uenced by a single gene. In this thesis it was hypothesised that examination of a renal microar- ray to compare the relative expression in F344 (susceptible) and Lewis (relatively protected) strains would reveal further genetic factors me- diating renal injury susceptibility. Genome wide expression analysis confirmed that Ace was a key modifier gene. Furthermore, the puriner- gic receptors P2x7 and P2x4 were identified as additional candidates. Gene and protein expression of these P2X receptors were both higher in F344 compared with Lewis. Immunohistochemistry localised P2X7 and P2X4 to the renal vasculature and tubules: the expression pattern was similar in both strains but became distinct in the renal medulla. F344, but not Lewis, responded to acute antagonism of P2X7 and P2X4. F344 showed a significant drop in blood pressure but maintained renal blood ow, indicative of tonic renal vasoconstriction. When ANG II was infused into F344 rats, there was a modest increase in blood pressure and an impairment of the pressure-natriuresis mecha- nism but no overt injury. Blood oxygenation-level dependent magnetic resonance imaging of the kidney identified a decrease in renal R2* sig- nal following P2X7 and P2X4 antagonism in ANG II infused F344 rats. P2X7/4 receptor activation reduces oxygenation and suppresses pressure-natriuresis. These effects are pro-biotic and may underpin susceptibility to renal injury.

Thesis (MScMed)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: In hypertrophic cardiomyopathy (HCM), an autosomal dominant disorder, hypertrophy is variable within and between families carrying the same causal mutation, suggesting a role for modifier genes. Associations between left ventricular hypertrophy and left ventricular pressure overload suggested that sequence variants in genes involved in the Renin-Angiotensin Aldosterone System (RAAS) may act as hypertrophy modifiers in HCM, but some of these studies may have been confounded by, amongst other things, lack of adjustment for hypertrophy covariates. To investigate this hypothesis, twenty one polymorphic loci spread across six genes (ACE1, AGT, AGTR1, CYP11B2, CMA and ACE2) of the RAAS were genotyped in 353 subjects from 22 South African HCM-families, in which founder mutations segregate. Genotypes were compared to 17 echocardiographically-derived hypertrophic indices of left ventricular wall thickness at 16 segments covering three longitudinal levels. Family-based association was performed by quantitative transmission disequilibrium testing (QTDT), and mixed effects models to analyse the X-linked gene ACE2, with concurrent adjustment for hypertrophy covariates (age, sex, systolic blood pressure (BP), diastolic BP, body surface area, heart rate and mutation status). Strong evidence of linkage in the absence of association was detected between polymorphisms at ACE1 and posterior and anterior wall thickness (PW and AW, respectively) at the papillary muscle level (pap) and apex level (apx). In single-locus analysis, statistically significant associations were generated between the CYP11B2 rs3097 polymorphism and PW at the mitral valve level (mit) and both PWpap and inferior wall thickness (IW)pap. Statistically significant associations were generated at three AGTR1 polymorphisms, namely, between rs2640539 and AWmit, rs 3772627 and anterior interventricular septum thickness at pap and rs5182 and both IWpap and AWapx. Furthermore, mixed effects model detected statistically significant association between the ACE2 rs879922 polymorphism and both posterior interventricular septum thickness and lateral wall thickness at mit in females only. These data indicate a role for RAAS gene variants, independent of hypertrophy covariates, in modifying the phenotypic expression of hypertrophy in HCM-affected individuals. / AFRIKAANSE OPSOMMING: Hipertrofiese kardiomiopatie (HCM), ‘n autosomale dominante afwyking, toon hoogs variërende hipertrofie binne en tussen families wat dieselfde siekte-veroorsakende mutasie het, hierdie dui op die moontlike betrokkenheid van geassosieerde modifiserende gene. Assosiasies tussen linker ventrikulêre hipertrofie en linker ventrikulêre druk-oorlading stel voor dat volgorde variasies in gene betrokke in die Renin-Angiotensin Aldosteroon Sisteem (RAAS) mag optree as hipertrofie modifiseerders in HCM. Sommige van hierdie soort studies is egter beperk omdat hulle nie gekompenseer het vir kovariante van hipertrofie nie. Om hierdie hipotese te ondersoek, is die genotipe bepaal by een-en-twintig polimorfiese lokusse, verspreid regoor ses RAAS gene (ACE1, AGT, AGTR1, CYP11B2, CMA and ACE2), in 353 kandidate vanuit 22 Suid-Afrikaanse HCM-families in wie stigter mutasies segregeer. Genotipes was vergelyk met 17 eggokardiografies afgeleide hipertrofiese indekse van linker ventrikulêre wanddikte by 16 segmente wat oor drie longitudinale vlakke strek. Familie-gebaseerde assosiasies was bestudeer deur kwantitatiewe transmissie disequilibrium toetsing (QTDT) en gemengde effek modelle om die X-gekoppelde geen ACE2 te analiseer, met gelyktydige kompensasie vir hipertrofie kovariate (ouderdom, geslag, sistoliese bloed druk (BP), diastoliese BP, liggaamsoppervlak area, hartritme en mutasie-status). Sterk indikasies van koppeling in die afwesigheid van assosiasie is waargeneem tussen ACE1 lokusse en posterior wanddikte (PW) asook anterior wanddikte (AW) by die papillêre spier vlak (pap) en die apeks vlak (apx). In enkel-lokus analises is statisties-betekenisvolle assosiasies gevind tussen die CYP11B2 rs3097 polimorfisme en PW by die mitraalklep vlak (mit) en beide die PWpap en inferior wanddikte (IW)pap. Statisties-betekenisvolle assosiasies was verder gevind by drie AGTR1 polimorfismes, naamlik, tussen rs2640539 polimorfisme en AWmit, rs3772627 en die anterior interventrikulêre septumdikte (aIVS) by die pap en rs5182 by beide die IWpap en AWapx. Gemengde-effek modelle het verder assosiasies aangetoon tussen die ACE2 rs879922 polimorfisme en die posterior interventrikulêre septumdikte en die laterale wanddikte by die mit, slegs in vrouens. Hierdie data dui op ‘n kovariaat-onafhanklike rol vir RAAS genetiese variante in die modifisering van die fenotipiese uitdrukking van hipertrofie in HCM-geaffekteerde individue.

Despite years of research, the role that hypovolemia plays in orthostatic intolerance after head down bed rest (BR) and spaceflight remains unclear. Additionally, the efficacy of oral saline countermeasures, employed in an attempt to restore plasma volume (PV) after BR is questionable. Several previous studies have suggested that a new homeostatic set point is achieved in space or during BR, making attempts to restore PV temporary at best. We tested the hypotheses that one day of BR would induce a transient increase in PV followed by hypovolemia and new hormonal balance; that a salt tablet and water fluid loading (FL) countermeasure would be ineffective in restoring PV; and also that the FL would not attenuate the exaggerated hormonal responses to orthostatic stress that are expected after 28hr of BR. Plasma volume, serum sodium and osmolarity, and plasma ANP, AVP, renin, angiotensin II, aldosterone, and catecholamines were measured in nine male subjects undergoing 5 different protocols (28hr Bed Rest without Fluid Loading = 28NFL, 28hr Bed Rest with Fluid Loading = 28FL, 4hr Seated Control = 4NFLS, 4hr Seated Control with Fluid Loading = 4FLS, and 4hr Bed Rest = 4BR) in a randomized repeated measures design. The FL countermeasure was 15 ml/kg of body weight of water with 1g of NaCl per 125ml of water. Orthostatic testing by lower body negative pressure (LBNP) was performed before and after all protocols. In agreement with our first hypothesis, we observed transient reductions in renin, angiotensin II, and aldosterone, which after 25.5hr were restored to baseline, slightly augmented, and suppressed, respectively. Also after 25.5hr, PV was reduced in the 28hr BR protocols and was not restored in 28FL; however, the FL protocol increased PV during 4FLS. We additionally observed augmented renin and aldosterone responses, as well as generally elevated angiotensin II after 28NFL, but not after 28FL or any of the 4hr protocols. Furthermore, no changes in plasma norepinephrine responses to LBNP were documented from Pre-Post test in any protocol. Our results indicate that: 1) PV is reduced after short term BR and is not restored by an oral FL; 2) renin-angiotensin-aldosterone system (RAAS) responses to orthostatic stress are augmented after 28hr of BR and the amplified response can be abrogated by FL; and 3) plasma norepinephrine responses during orthostatic stress are not affected by BR or FL, suggesting that RAAS activity may be modulated by FL independently of sympathetic activity and PV during orthostasis after bed rest.

Despite years of research, the role that hypovolemia plays in orthostatic intolerance after head down bed rest (BR) and spaceflight remains unclear. Additionally, the efficacy of oral saline countermeasures, employed in an attempt to restore plasma volume (PV) after BR is questionable. Several previous studies have suggested that a new homeostatic set point is achieved in space or during BR, making attempts to restore PV temporary at best. We tested the hypotheses that one day of BR would induce a transient increase in PV followed by hypovolemia and new hormonal balance; that a salt tablet and water fluid loading (FL) countermeasure would be ineffective in restoring PV; and also that the FL would not attenuate the exaggerated hormonal responses to orthostatic stress that are expected after 28hr of BR. Plasma volume, serum sodium and osmolarity, and plasma ANP, AVP, renin, angiotensin II, aldosterone, and catecholamines were measured in nine male subjects undergoing 5 different protocols (28hr Bed Rest without Fluid Loading = 28NFL, 28hr Bed Rest with Fluid Loading = 28FL, 4hr Seated Control = 4NFLS, 4hr Seated Control with Fluid Loading = 4FLS, and 4hr Bed Rest = 4BR) in a randomized repeated measures design. The FL countermeasure was 15 ml/kg of body weight of water with 1g of NaCl per 125ml of water. Orthostatic testing by lower body negative pressure (LBNP) was performed before and after all protocols. In agreement with our first hypothesis, we observed transient reductions in renin, angiotensin II, and aldosterone, which after 25.5hr were restored to baseline, slightly augmented, and suppressed, respectively. Also after 25.5hr, PV was reduced in the 28hr BR protocols and was not restored in 28FL; however, the FL protocol increased PV during 4FLS. We additionally observed augmented renin and aldosterone responses, as well as generally elevated angiotensin II after 28NFL, but not after 28FL or any of the 4hr protocols. Furthermore, no changes in plasma norepinephrine responses to LBNP were documented from Pre-Post test in any protocol. Our results indicate that: 1) PV is reduced after short term BR and is not restored by an oral FL; 2) renin-angiotensin-aldosterone system (RAAS) responses to orthostatic stress are augmented after 28hr of BR and the amplified response can be abrogated by FL; and 3) plasma norepinephrine responses during orthostatic stress are not affected by BR or FL, suggesting that RAAS activity may be modulated by FL independently of sympathetic activity and PV during orthostasis after bed rest.

No description available.

In 2008 the global prevalence of hypertension [high blood pressure (BP), systolic ≥140 mmHg and/or diastolic ≥90 mmHg] was around 40% in adults > 25 yrs of age, according to the 2013 WHO statistics. Hypertension is a major risk factor for myocardial infarction, heart failure and stroke. Currently, around 20% of the Canadian population is affected by hypertension. Hypertension is more closely associated with diabetes. More than two thirds of people with diabetes have hypertension, alongwith increased activity of the renin angiotensin aldosterone (RAAS) system. The RAAS plays a major role in maintaining fluid balance, vascular tone and BP. The components of the RAAS include the hormone renin, which cleaves angiotensinogen, a circulating inactive peptide into angiotensin I. Angiotensin converting enzyme (ACE) converts angiotensin I into the active peptide angiotensin II (Ang II). Ang II causes vasoconstriction, sodium reabsorption from the kidney tubules and also release of the hormone, aldosterone, from the adrenal cortex. The epidemic of hypertension, diabetes and obesity is widely attributed to a high carbohydrate diet, containing mainly high fructose corn syrup and sucrose. However, the underlying molecular mechanisms are far from clear. A high fructose diet increases BP in Sprague-Dawley (SD) rats; along with elevated plasma and aortic levels of methylglyoxal (MG). MG is a reactive dicarbonyl compound mainly formed as an intermediate during glycolysis. Small amounts of MG are also formed during amino acid (threonine) and fatty acid metabolism. MG reacts with certain proteins to form irreversible advanced glycation end products (AGEs). MG has high affinity for arginine, lysine and cysteine. Plasma MG levels are increased in hypertensive rats and diabetic patients. However, it is not yet clear whether MG is the cause or effect of hypertension. Moreover, safe and specific MG scavengers are not available. The aim of the project was to determine the effect of MG and a high fructose diet on the RAAS and the BP in male SD rats. The hypothesis that L-arginine, and its inactive isomer D-arginine, can efficiently scavenge MG in vitro, was also tested. Male SD rats were treated with a continuous infusion of MG with a subcutaneous minipump for 4 weeks, or with a high fructose diet (60% of total calories) for 16 weeks. We also used isolated aortic rings from 12 week old normal male SD rats to study endothelial function. Organs / tissues, cultured human umbilical vein endothelial cells (HUVECs) and vascular smooth muscle cells (VSMCs) were used for molecular studies. HPLC, Western blotting and Q-PCR were used to measure MG, reduced glutathione (GSH), proteins and mRNA, respectively. siRNA for angiotensinogen and the receptor for advanced glycation endproducts (RAGE) were used to study mechanisms. MG treated rats developed a significant increase in BP and plasma levels of aldosterone, renin, angiotensin and catecholamines. MG level, and protein and mRNA for angiotensin, AT1 receptor, adrenergic α1D receptor and renin were significantly increased in the aorta and/or kidney of MG treated rats, a novel finding. Alagebrium, a MG scavenger and AGEs breaker, attenuated the above effects of MG. Treatment of cultured VSMCs with MG or high glucose (25mM) significantly increased cellular MG, and protein and mRNA for nuclear factor kappa B (NF-κB), angiotensin, AT1 and α1D receptors, which were prevented by inhibition of NF-κB, and by alagebrium. Silencing of mRNA for RAGE prevented the increase in NF-kB induced by MG. Silencing of mRNA for angiotensinogen prevented the increase in NF-κB, angiotensin, AT1 and α1D receptors’ protein. Fructose treated rats developed a significant increase in BP. MG level and protein and mRNA for angiotensin II, AT1 receptor, adrenergic α1D receptor and renin were significantly increased, whereas GSH levels were decreased, in the aorta and/or kidney of fructose fed rats. The protein expression of the receptor for AGEs (RAGE) and NF-κB were also significantly increased in the aorta of fructose fed rats. MG treated VSMCs showed increased protein for angiotensin II, AT1 receptor, and α1D receptor. The effects of fructose and MG were attenuated by metformin, a MG scavenger and AGEs inhibitor. In experiments to test the MG scavenging action of arginine, both D-arginine and L-arginine prevented the attenuation of acetylcholine-induced endothelium-dependent vasorelaxation by MG and high glucose. However, the inhibitory effect of the NOS inhibitor, Nω-nitro-L-arginine methyl ester, on vasorelaxation was prevented only by L-arginine, but not by D-arginine. MG and high glucose increased protein expression of arginase, a novel finding, and also of NADPH oxidase 4 and NF-κB, and production of reactive oxygen species in HUVECs and VSMCs, which were attenuated by D- and L-arginine. However, D- and L-arginine did not attenuate MG and high glucose-induced increased arginase activity in VSMCs and the aorta. D- and L-arginine also attenuated the increased formation of the MG-specific AGE, Nε-carboxyethyl lysine, caused by MG and high glucose in VSMCs. In conclusion, MG activates NF-κB through RAGE and thereby increases renin angiotensin levels, a novel finding, and a probable mechanism of increase in BP. There is a strong association between elevated levels of MG, RAGE, NF-κB, mediators of the RAAS and BP in high fructose diet fed rats. Arginine attenuates the increased arginase expression, oxidative stress, endothelial dysfunction and AGEs formation induced by MG and high glucose, by an endothelial NOS independent mechanism.

Despite the number of therapeutic interventions currently available for treating hypertension, approximately one-third of adult patients in the United States currently being treated remain hypertensive (43). As the number of hypertensive patients continues to grow, it is becoming increasingly important to investigate the different types of hypertension in order to have a greater understanding of the pathogenesis and identify potential targets for treatment. Neurogenic hypertension refers to hypertension resulting from a centrally mediated mechanism, likely involving a sustained increase in sympathetic nervous system activity. The renin-angiotensin aldosterone system (RAAS) is a physiological cascade responsible for restoring blood pressure when it drops. The rate-limiting step involves the enzyme renin. Although there is evidence of local RAAS activity in the brain, expression of renin in the brain is very low (125). The (pro)renin receptor ((P)RR) is able to bind and activate both renin and (pro)renin. Because the (P)RR and (pro)renin expression is high in the brain, it is possible that local RAAS activity is orchestrated by the (P)RR. In this study, we investigated if neuroinflammatory conditions could foster an environment that would allow for a rise in sympathetic nervous system activity (SNA) resulting from brain RAAS activity and the (P)RR. By treating neuronal cell cultures with proinflammatory cytokines, an anti-inflammatory agent, and (pro)renin, we explored any changes or differences in mRNA expression levels. Additionally, the effects of antioxidants were investigated. The results of this study showed that cells lacking antioxidants were more vulnerable to cellular stress and inflammation in the presence of increased (pro)renin. Proinflammatory stress was correlated with increased mRNA expression of proinflammatory and immune system regulatory genes in addition to increased expression of angiotensin II type I receptor, a vital component of RAAS. This could indicate that neuroinflammatory stress can be exacerbated and contribute to increased RAAS activity in the brain mediated by the (P)RR.

The prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) quickly reached pandemic proportions, and knowledge about this virus and coronavirus disease 2019 (COVID-19) has expanded rapidly. This review focuses primarily on mechanisms that contribute to acute cardiac injury and dysfunction, which are common in patients with severe disease. The etiology of cardiac injury is multifactorial, and the extent is likely enhanced by pre-existing cardiovascular disease. Disruption of homeostatic mechanisms secondary to pulmonary pathology ranks high on the list, and there is growing evidence that direct infection of cardiac cells can occur. Angiotensin converting enzyme 2 (ACE2) plays a central role in COVID-19 and is a necessary receptor for viral entry into human cells. ACE2 normally not only eliminates angiotensin II (Ang II) by converting it to Ang (1-7), but also elicits a beneficial response profile counteracting that of Ang II. Molecular analyses of single nuclei from human hearts have shown that ACE2 is most highly expressed by pericytes. Given the important roles that pericytes have in the microvasculature, infection of these cells could compromise myocardial supply to meet metabolic demand. Furthermore, ACE2 activity is crucial for opposing adverse effects of locally generated Ang II, so virus-mediated internalization of ACE2 could exacerbate pathology by this mechanism. While the role of cardiac pericytes in acute heart injury by SARS-CoV-2 requires investigation, expression of ACE2 by these cells has broader implications for cardiac pathophysiology.

Thesis (MScMedSc (Biomedical Sciences. Molecular Biology and Human Genetics))--University of Stellenbosch, 2009. / Hypertrophic cardiomyopathy (HCM), an inherited primary cardiac disorder mostly caused by defective sarcomeric proteins, is considered a model for studying left ventricular hypertrophy (LVH) in the absence of increased external loading conditions. The disease manifests extreme variability in the degree and pattern of LVH, even in HCM patients with the same causal mutation. The clinical phenotype of HCM can therefore be viewed as a product of the effect of sarcomere dysfunction and of additional genetic modifiers. Components of the renin-angiotensin-aldosterone system (RAAS) are plausible candidate modifiers because of their effect on blood pressure and their direct hypertrophic effect on cardiomyocytes. The present study investigated genes encoding components of the RAAS for association with cardiac hypertrophy traits, in 353 individuals comprised of genetically and echocardiographically affected and unaffected family members, belonging to 22 HCM families with HCM founder mutations by employing a multi-SNP approach with TaqMan allelic discrimination technology. Gene-gene interaction analysis was also performed to investigate the effect of epistasis on hypertrophy. Candidate genes for analysis included the angiotensin II type 2 receptor (AT2 receptor), renin, renin-binding protein (RnBP), the (pro)renin receptor, the mineralocorticoid receptor as well as genes encoding subunits of the epithelial sodium channels (ENaC) and Na+/K+-ATPase that showed evidence for cardiac expression. The present study demonstrates for the first time that variations in the renin and RnBP genes play a role in modulating hypertrophy in HCM, independent of blood pressure and confirms the involvement of the AT2 receptor in hypertrophy in HCM. Additionally we report an association between Na+/K+-ATPase α1- and β1-subunits as well as the ENaC α- and β-subunits and hypertrophy. Significant evidence for epistasis was found between renin and downstream RAAS effectors, suggesting a complex interplay between these RAAS variants and the hypertrophic phenotype in HCM. The identification of such modifiers for HCM may offer novel targets for hypertrophy research and ultimately antihypertrophic therapy.

A Abstinência ao Etanol (AE) é uma complicação de curta duração desenvolvida após a interrupção parcial ou total do consumo crônico de etanol. Alguns dos sintomas descritos incluem: aumento transitório da pressão arterial, alteração da resistência vascular periférica e alterações comportamentais; entretanto, os mecanismos envolvidos nessas respostas continuam elusivos. O objetivo desse estudo foi o de investigar os efeitos da abstinência ao etanol sobre o sistema renina-angiotensina-aldosterona (SRAA) e a função vascular. Ratos Wistar (250g) foram divididos em 3 grupos: Controle (CTR): os animais receberam água ad libitum por 23 dias; Etanol (EtOH): o tratamento crônico com etanol foi iniciado com uma solução de etanol 3% (vol./vol.), sendo gradualmente aumentada a cada três dias para 6% (4º dia) e 9% (7º dia em diante), mantendo-se esta concentração até o 21° dia; Abstinência ao Etanol (AE): os animais foram tratados da mesma maneira que o grupo EtOH até o 20º dia, neste dia a solução de etanol 9% foi retirada e retornada no dia seguinte (21º dia) por apenas 2h; após o término deste período, os animais receberam água até o dia do teste (23º dia), garantindo assim, o quadro de abstinência por 48h. Para avaliar o comportamento, os animais foram testados no Labirinto em Cruz Elevado (LCE). A pressão arterial foi medida por pletismografia de cauda. Foram avaliados os níveis plasmáticos de: a) etanol por cromatografia gasosa; b) corticosterona (CORT), angiotensina I e II (ANGI e II), vasopressina (AVP), ocitocina e peptídeo natriurético atrial (ANP) por radioimunoensaio; c) aldosterona (ALDO), renina (REN) e espécies reativas de oxigênio ao ácido tiobarbitúrico (TBARS) por ELISA; atividade plasmática da enzima conversora de angiotensina por fluorímetria; d) atividade da NAD(P)H-oxidase em aorta e leito mesentérico pelo método de quimioluminescência da lucigenina; d) de sódio (Na+ ) por fotometria de chama; e) osmolaridade foi medida pelo abaixamento do ponto de congelamento da água. Foi realizada avaliação da reatividade vascular em aorta isolada para angiotensina II (ANG II), fenilefrina, cloreto de potássio, acetilcolina e nitroprussiato de sódio (NPS). A abstinência ao etanol promoveu diminuição significativa da porcentagem de entrada e tempo despendido nos braços abertos do LCE; além disso, houve aumento da concentração plasmática de corticosterona. Em conjunto estes resultados mostram o efeito ansiogênico da abstinência ao etanol. A abstinência ao etanol também promoveu aumento da pressão arterial sistólica e média. Houve aumento do estresse oxidativo sistêmico e tecidual. Em relação ao balanço hidroeletrolítico, não foi encontrada nenhuma alteração induzida pela abstinência ao etanol. A abstinência ao etanol induziu alterações vasculares independentes de endotélio representada por diminuição da contração para ANG II, fenilefrina e KCl e aumento do relaxamento para o nitroprussiato de sódio. A partir destes resultados podemos concluir que a abstinência ao etanol induz ansiedade, estimula o SRAA, induz hipertensão e estresse oxidativo e altera a função vascular de maneira independente de endotélio. / Ethanol withdrawal is a short-term complication developed after partial or total interruption of chronic ethanol consumption. Some of the symptoms described include: transient increase in blood pressure, peripheral vascular resistance changes and behavioral changes, however, the mechanisms involved in these responses remain elusive. The aim of this study was to investigate the effects of ethanol withdrawal on the renin-angiotensin-aldosterone system (RAAS) and vascular function. With this purpose, male Wistar rats (250g) were divided into 3 groups: control (CTR): animals received water ad libitum for 23 days, ethanol (EtOH): chronic treatment with ethanol was started with an ethanol solution 3% (vol. / vol.) being gradually increased every three days to 6% (day 4) and 9% (day 7 onwards), being this concentration maintained until day 21; Ethanol abstinence (EA): animals were treated in the same way of the EtOH group until day 20. Then, ethanol solution 9% was removed and returned the next day (day 21) for 2h. After the end of this period, the animals received water until day 23, ensuring abstinence for 48 hours. Animals were tested on the Elevated Plus Maze (EPM). Blood pressure was measured by tail plethysmography. Plasma levels of: a) ethanol were determined by gas chromatography, b) corticosterone (CORT), angiotensin I and II (ANGI and II), vasopressin (AVP), oxytocin, and atrial natriuretic peptide (ANP) by radioimmunoassay; c ) aldosterone (ALDO), plasma activity of angiotensin converting enzyme by fluorimetry; renin (REN) and thiobarbituric acid reactive substances (TBARS) by ELISA; d) activity of NAD (P)H in the aorta and mesenteric arterial bed by lucigenin chemiluminescence assay; d) sodium (Na+ ) by photometry; e) osmolarity was measured by the lowering of the freezing point of water. Vascular reactivity of isolated aorta to angiotensin II (ANG II), phenylephrine, KCl, acetylcholine, and sodium nitroprusside (SNP) was evaluated. Abstinence to ethanol induced a significant reduction in the percentage of entries and time spent in the open arms of the EPM. Increased corticosterone plasma levels were also detected in animals from the EA group. Together these findings suggest that abstinence to ethanol induces an anxiogenic-like effect. Abstinence to ethanol induced an increase in plasma ANG II with no changes on ANG I, renin or aldosterone levels. The levels of ANG I and ANG II in the aorta and mesenteric arterial bed were not altered in animals from the EA group. Abstinence to ethanol also induced increase in systolic blood pressure and mean arterial blood pressure. Abstinence to ethanol increased systemic oxidative stress and the vascular generation of superoxide anion. No change in the fluid balance was detected in animals from the EA group. In endothelium-denuded, but not intact aortic rings, abstinence to ethanol decreased the contraction induced by ANG II, phenylephrine and KCl. Increased NPS-induced relaxation was also observed in rings from EA animals. We conclude that ethanol withdrawal: a) induces anxiety; b) stimulates the systemic RAAS; c) increases blood pressure; d) induces systemic and vascular oxidative stress; e) alters the vascular function in an endothelium-independent manner.