937 resultados para ambulatory arterial blood pressure monitoring


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We determined the effects of two classical angiotensin II (ANG II) antagonists, [Sar(1), Ala(8)]-ANG II and [Sar(1), Thr(8)]-ANG II, and losartan (a nonpeptide and selective antagonist for the AT 1 angiotensin receptors) on diuresis, natriuresis, kaliuresis and arterial blood pressure induced by ANG II administration into the median preoptic nucleus (MnPO) of male Holtzman rats weighing 250-300 g. Urine was collected in rats submitted to a water load (5% body weight) by gastric gavage, followed by a second water load (5% body weight) 1 h later. The volume of the drug solutions injected was 0.5 mu l over 10-15 s. Pre-treatment with [Sar(1), Ala(8)]-ANG II (12 rats) and [Sar(1), Thr(8)]-ANG II (9 rats), at the dose of 60 ng reduced (13.7 +/- 1.0 vs 11.0 +/- 1.0 and 10.7 +/- 1.2, respectively), whereas losartan (14 rats) at the dose of 160 ng totally blocked (13.7 +/- 1.0 vs 7.6 +/- 1.5) the urine excretion induced by injection of 12 ng of ANG II (14 rats). [Sar(1), Ala(8)]-ANG II impaired Na+ excretion (193 +/- 16 vs 120 +/- 19): whereas [Sar(1), Thr(8)]-ANG II and losartan blocked Na+ excretion (193 +/- 16 vs 77 +/- 15 and 100 +/- 12, respectively) induced by ANG II. Similar effects induced by ANG II on K+ excretion were observed with [Sar(1), Ala(8)]-ANG II, [Sar(1), Thr(8)]-ANG II, and losartan pretreatment (133 +/- 18 vs 108 +/- 11, 80 +/- 12, and 82 +/- 15, respectively). The same doses as above of [Sar(1), Ala(8)]-ANG II (8 rats), [Sar(1), Thr(8)]-ANG II (8 rats). and losartan (9 rats) blocked the increase in the arterial blood pressure induced by 12 ng of ANG II (12 rats) (32 +/- 4 ru 4 +/- 2, 3.5 +/- 1, and 2 +/- 1: respectively. The results indicate that the AT1 receptor subtype participates in the increases of diuresis, natriuresis. kaliuresis and arterial blood pressure induced by the administration of ANG II into the MnPO.

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Pulmonary thromboembolism (PTE) ranges from incidental, clinically unimportant thromboembolism to massive embolism with sudden death. Its treatment is well established in two groups of patients: heparin for those with normal systemic blood pressure without right ventricular dysfunction (RVD) and thrombolysis for those with RVD and circulatory shock. In an intermediate group of patients with systemic blood pressure stability combined with RVD, which is usually associated with worse outcome, the treatment is controversial. There are authors who strongly suggest thrombolysis while others contraindicate this procedure and recommend anticoagulation with heparin. This is a narrative review that includes clinical trials comparing thrombolysis and heparin for the treatment of PTE patients with systemic blood pressure stability and RVD published since 1973. The results show that there are only four trials on this subject with less than 500 patients. Many PTE patients with systemic blood pressure stability and RVD might benefit from thrombolysis but, on the other hand, the risk for hemorrhagic events may be increased. Large randomized clinical trials are required to clarify this. © 2008 Bentham Science Publishers Ltd.

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Aims The macrophage migration inhibitory factor (MIF) is an intracellular inhibitor of the central nervous system actions of angiotensin II on blood pressure. Considering that angiotensin II actions at the nucleus of the solitary tract are important for the maintenance of hypertension in spontaneously hypertensive rats (SHRs), we tested if increased MIF expression in the nucleus of the solitary tract of SHR alters the baseline high blood pressure in these rats.Methods and resultsEight-week-old SHRs or normotensive rats were microinjected with the vector AAV2-CBA-MIF into the nucleus of the solitary tract, resulting in MIF expression predominantly in neurons. Rats also underwent recordings of the mean arterial blood pressure (MAP) and heart rate (via telemetry devices implanted in the abdominal aorta), cardiac- and baroreflex function. Injections of AAV2-CBA-MIF into the nucleus of the solitary tract of SHRs produced significant decreases in the MAP, ranging from 10 to 20 mmHg, compared with age-matched SHRs that had received identical microinjections of the control vector AAV2-CBA-eGFP. This lowered MAP in SHRs was maintained through the end of the experiment at 31 days, and was associated with an improvement in baroreflex function to values observed in normotensive rats. In contrast to SHRs, similar increased MIF expression in the nucleus of the solitary tract of normotensive rats produced no changes in baseline MAP and baroreflex function.ConclusionThese results indicate that an increased expression of MIF within the nucleus of the solitary tract neurons of SHRs lowers blood pressure and restores baroreflex function. © 2012 Published on behalf of the European Society of Cardiology. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Previous studies have shown that fresh squeezed orange juice or juice from reconstituted concentrate can help prevent the development of atherosclerosis. Pasteurized orange juice presently represents the major orange juice available in the market, and because of this, it becomes necessary to determine the healthy benefits associated with this product. In this study we investigated the effect of regular consumption of pasteurized orange juice on the nutritional status, biochemical profile, and arterial blood pressure in healthy men and women. Men and women volunteered to consume pasteurized orange juice (500 mL·d–1 and 750 mL·d–1, respectively), for 8 weeks. Anthropometric, biochemical, hemodynamic, and dietary assessments were evaluated at baseline and at the end of the experimental period. Total cholesterol and LDL-C significantly decreased in both men and women after the consumption of orange juice, and an increase in HDL-C level was detected exclusively in women. Fasting glucose, diastolic blood pressure, and triglyceride levels dropped in men after the consumption of orange juice. Anthropometric variables did not change with orange juice consumption, only waist circumference decreased significantly in women. Consumption of orange juice increased the energy and carbohydrate intake for women; however, vitamin C and folate increased after the orange juice period for both men and women. Regular consumption of pasteurized orange juice by men (750 mL·d–1) and women (500 mL·d–1) reduced the risk of developing atherosclerosis, and increased the nutritional quality of their diets.

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Background: Although plasmid DNA encoding an antigen from pathogens or tumor cells has been widely studied as vaccine, the use of plasmid vector (without insert) as therapeutic agent requires further investigation. Results: Here, we showed that plasmid DNA (pcDNA3) at low doses inhibits the production of IL-6 and TNF-alpha by lipopolysaccharide (LPS)-stimulated macrophage cell line J774. These findings led us to evaluate whether plasmid DNA could act as an anti-inflammatory agent in a Wistar rat endotoxemia model. Rats injected simultaneously with 1.5 mg/kg of LPS and 10 or 20 mu g of plasmid DNA had a remarkable attenuation of mean arterial blood pressure (MAP) drop at 2 hours after treatment when compared with rats injected with LPS only. The beneficial effect of the plasmid DNA on MAP was associated with decreased expression of IL-6 in liver and increased concentration of plasma vasopressin (AVP), a known vasoconstrictor that has been investigated in hemorrhagic shock management. No difference was observed in relation to nitric oxide (NO) production. Conclusion: Our results demonstrate for the first time that plasmid DNA vector at low doses presents anti-inflammatory property and constitutes a novel approach with therapeutic potential in inflammatory diseases.

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[EN] Chronic hypoxia is associated with elevated sympathetic activity and hypertension in patients with chronic pulmonary obstructive disease. However, the effect of chronic hypoxia on systemic and regional sympathetic activity in healthy humans remains unknown. To determine if chronic hypoxia in healthy humans is associated with hyperactivity of the sympathetic system, we measured intra-arterial blood pressure, arterial blood gases, systemic and skeletal muscle noradrenaline (norepinephrine) spillover and vascular conductances in nine Danish lowlanders at sea level and after 9 weeks of exposure at 5260 m. Mean blood pressure was 28 % higher at altitude (P < 0.01) due to increases in both systolic (18 % higher, P < 0.05) and diastolic (41 % higher, P < 0.001) blood pressures. Cardiac output and leg blood flow were not altered by chronic hypoxia, but systemic vascular conductance was reduced by 30 % (P < 0.05). Plasma arterial noradrenaline (NA) and adrenaline concentrations were 3.7- and 2.4-fold higher at altitude, respectively (P < 0.05). The elevation of plasma arterial NA concentration was caused by a 3.8-fold higher whole-body NA release (P < 0.001) since whole-body noradrenaline clearance was similar in both conditions. Leg NA spillover was increased similarly (x 3.2, P < 0.05). These changes occurred despite the fact that systemic O2 delivery was greater after altitude acclimatisation than at sea level, due to 37 % higher blood haemoglobin concentration. In summary, this study shows that chronic hypoxia causes marked activation of the sympathetic nervous system in healthy humans and increased systemic arterial pressure, despite normalisation of the arterial O2 content with acclimatisation.

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Renal allograft donors are at risk of developing hypertension. Here, we hypothesized that this risk is at least in part explained by an enhanced intracellular availability of 11β-hydroxyglucocorticoids due to an increased 11β-hydroxysteroid dehydrogenase type 1 enzyme (11β-HSD1), an intracellular prereceptor activator of biologically inactive 11-ketocorticosteroids in the liver, and/or a diminished 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), an inactivator of 11β-hydroxyglucocorticoids in the kidney. To test this hypothesis, uninephrectomized (UNX) (n=9) and sham-operated (n=10) adult Sprague-Dawley rats were investigated. Mean arterial blood pressure and heart rate were measured continuously by telemetry for 6 days in week 5 after UNX. The mRNA of 11β-Hsd1 and 11β-Hsd2 in liver and kidney tissues were assessed by RT-PCR and the 11β-HSD activities were directly quantified in their corresponding tissues by determining the ratios of (tetrahydrocorticosterone+5α-tetrahydrocorticosterone)/tetrahydrodehydrocorticosterone ((THB+5α-THB)/THA) and of corticosterone/dehydrocorticosterone (B/A) by gas chromatography-mass spectrometry. The apparent total body activities of 11β-HSD1 and 11β-HSD2 were estimated using the urinary and plasma ratios of (THB+5α-THB)/THA and B/A. Mean arterial blood pressure was increased after UNX when compared with sham operation. Hepatic mRNA content of 11β-Hsd1 and hepatic, plasma, and urinary ratios of (THB+5α-THB)/THA were decreased after UNX, indicating diminished access of glucocorticoids to its receptors. In renal tissue, 11β-Hsd2 mRNA was reduced and B/A ratios measured in kidney, plasma, and urine were increased, indicating reduced 11β-HSD2 activity and enhanced access of glucocorticoids to mineralocorticoid receptors. Both 11β-HSD1 and 11β-HSD2 are downregulated after UNX in rats, a constellation considered to induce hypertension.

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ABSTRACT: INTRODUCTION: Low blood pressure, inadequate tissue oxygen delivery and mitochondrial dysfunction have all been implicated in the development of sepsis-induced organ failure. This study evaluated the effect on liver mitochondrial function of using norepinephrine to increase blood pressure in experimental sepsis. METHODS: Thirteen anaesthetized pigs received endotoxin (Escherichia coli lipopolysaccharide B0111:B4; 0.4 mug/kg per hour) and were subsequently randomly assigned to norepinephrine treatment or placebo for 10 hours. Norepinephrine dose was adjusted at 2-hour intervals to achieve 15 mmHg increases in mean arterial blood pressure up to 95 mmHg. Systemic (thermodilution) and hepatosplanchnic (ultrasound Doppler) blood flow were measured at each step. At the end of the experiment, hepatic mitochondrial oxygen consumption (high-resolution respirometry) and citrate synthase activity (spectrophotometry) were assessed. RESULTS: Mean arterial pressure (mmHg) increased only in norepinephrine-treated animals (from 73 [median; range 69 to 81] to 63 [60 to 68] in controls [P = 0.09] and from 83 [69 to 93] to 96 [86 to 108] in norepinephrine-treated animals [P = 0.019]). Cardiac index and systemic oxygen delivery (DO2) increased in both groups, but significantly more in the norepinephrine group (P < 0.03 for both). Cardiac index (ml/min per.kg) increased from 99 (range: 72 to 112) to 117 (110 to 232) in controls (P = 0.002), and from 107 (84 to 132) to 161 (147 to 340) in norepinephrine-treated animals (P = 0.001). DO2 (ml/min per.kg) increased from 13 (range: 11 to 15) to 16 (15 to 24) in controls (P = 0.028), and from 16 (12 to 19) to 29 (25 to 52) in norepinephrine-treated animals (P = 0.018). Systemic oxygen consumption (systemic VO2) increased in both groups (P < 0.05), whereas hepatosplanchnic flows, DO2 and VO2 remained stable. The hepatic lactate extraction ratio decreased in both groups (P = 0.05). Liver mitochondria complex I-dependent and II-dependent respiratory control ratios were increased in the norepinephrine group (complex I: 3.5 [range: 2.1 to 5.7] in controls versus 5.8 [4.8 to 6.4] in norepinephrine-treated animals [P = 0.015]; complex II: 3.1 [2.3 to 3.8] in controls versus 3.7 [3.3 to 4.6] in norepinephrine-treated animals [P = 0.09]). No differences were observed in citrate synthase activity. CONCLUSION: Norepinephrine treatment during endotoxaemia does not increase hepatosplanchnic flow, oxygen delivery or consumption, and does not improve the hepatic lactate extraction ratio. However, norepinephrine increases the liver mitochondria complex I-dependent and II-dependent respiratory control ratios. This effect was probably mediated by a direct effect of norepinephrine on liver cells.

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BACKGROUND AND PURPOSE: Transient elevation of arterial blood pressure (BP) is frequent in acute ischemic stroke and may help to increase perfusion of tissue jeopardized by ischemia. If this is true, recanalization may eliminate the need for this BP elevation. METHODS: We analyzed BP in 149 patients with acute ischemic stroke on admission to the hospital and 1 and 12 hours after intraarterial thrombolysis. BP values of patients with adequate recanalization were compared with BP values of patients with inadequate recanalization. Recanalization was determined on cerebral arteriography after thrombolysis using thrombolysis in myocardial infarction grades. RESULTS: Systolic, mean, and diastolic arterial BP decreased significantly from admission to 12 hours after thrombolysis in all patients (P<0.001). Before thrombolysis, patients with adequate and inadequate recanalization showed equal systolic (147.4 and 148.0 mm Hg), mean (102.1 and 104.1 mm Hg), and diastolic (79.5 and 82.1 mm Hg) BP values. Twelve hours after thrombolysis, patients with adequate recanalization had lower values than those with inadequate recanalization (systolic BP, 130 versus 139.9 mm Hg; mean BP, 86.8 versus 92.2 mm Hg; and diastolic, BP 65.2 versus 68.3 mm Hg). Two-way repeated ANOVA analysis showed a significant group x time interaction for systolic BP, indicating a larger systolic BP decrease when recanalization succeeded (P=0.019). CONCLUSIONS: The course of elevated systolic but not diastolic BP after acute ischemic stroke was found to be inversely associated with the degree of vessel recanalization. When recanalization failed, systolic BP remained elevated longer than when it succeeded.

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Definitions of shock and resuscitation endpoints traditionally focus on blood pressures and cardiac output. This carries a high risk of overemphasizing systemic hemodynamics at the cost of tissue perfusion. In line with novel shock definitions and evidence of the lack of a correlation between macro- and microcirculation in shock, we recommend that macrocirculatory resuscitation endpoints, particularly arterial and central venous pressure as well as cardiac output, be reconsidered. In this viewpoint article, we propose a three-step approach of resuscitation endpoints in shock of all origins. This approach targets only a minimum individual and context-sensitive mean arterial blood pressure (for example, 45 to 50 mm Hg) to preserve heart and brain perfusion. Further resuscitation is exclusively guided by endpoints of tissue perfusion irrespectively of the presence of arterial hypotension ('permissive hypotension'). Finally, optimization of individual tissue (for example, renal) perfusion is targeted. Prospective clinical studies are necessary to confirm the postulated benefits of targeting these resuscitation endpoints.

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UNLABELLED Obstructive sleep apnea (OSA) is a frequent syndrome characterized by intermittent hypoxemia and increased prevalence of arterial hypertension and cardiovascular morbidity. In OSA, the presence of patent foramen ovale (PFO) is associated with increased number of apneas and more severe oxygen desaturation. We hypothesized that PFO closure improves sleep-disordered breathing and, in turn, has favorable effects on vascular function and arterial blood pressure. In 40 consecutive patients with newly diagnosed OSA, we searched for PFO. After initial cardiovascular assessment, the 14 patients with PFO underwent initial device closure and the 26 without PFO served as control group. Conventional treatment for OSA was postponed for 3 months in both groups, and polysomnographic and cardiovascular examinations were repeated at the end of the follow-up period. PFO closure significantly improved the apnea-hypopnea index (ΔAHI -7.9±10.4 versus +4.7±13.1 events/h, P=0.0009, PFO closure versus control), the oxygen desaturation index (ΔODI -7.6±16.6 versus +7.6±17.0 events/h, P=0.01), and the number of patients with severe OSA decreased significantly after PFO closure (79% versus 21%, P=0.007). The following cardiovascular parameters improved significantly in the PFO closure group, although remained unchanged in controls: brachial artery flow-mediated vasodilation, carotid artery stiffness, nocturnal systolic and diastolic blood pressure (-7 mm Hg, P=0.009 and -3 mm Hg, P=0.04, respectively), blood pressure dipping, and left ventricular diastolic function. In conclusion, PFO closure in OSA patients improves sleep-disordered breathing and nocturnal oxygenation. This translates into an improvement of endothelial function and vascular stiffening, a decrease of nighttime blood pressure, restoration of the dipping pattern, and improvement of left ventricular diastolic function. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01780207.

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To investigate the functional role of different α1-adrenergic receptor (α1-AR) subtypes in vivo, we have applied a gene targeting approach to create a mouse model lacking the α1b-AR (α1b−/−). Reverse transcription–PCR and ligand binding studies were combined to elucidate the expression of the α1-AR subtypes in various tissues of α1b +/+ and −/− mice. Total α1-AR sites were decreased by 98% in liver, 74% in heart, and 42% in cerebral cortex of the α1b −/− as compared with +/+ mice. Because of the large decrease of α1-AR in the heart and the loss of the α1b-AR mRNA in the aorta of the α1b−/− mice, the in vivo blood pressure and in vitro aorta contractile responses to α1-agonists were investigated in α1b +/+ and −/− mice. Our findings provide strong evidence that the α1b-AR is a mediator of the blood pressure and the aorta contractile responses induced by α1 agonists. This was demonstrated by the finding that the mean arterial blood pressure response to phenylephrine was decreased by 45% in α1b −/− as compared with +/+ mice. In addition, phenylephrine-induced contractions of aortic rings also were decreased by 25% in α1b−/− mice. The α1b-AR knockout mouse model provides a potentially useful tool to elucidate the functional specificity of different α1-AR subtypes, to better understand the effects of adrenergic drugs, and to investigate the multiple mechanisms involved in the control of blood pressure.

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Les Erythropoietin-producing hepatocyte (EPH) sont la plus grande famille de récepteurs tyrosine kinase. Leurs ligands, les éphrines (EFNs), sont aussi des molécules exprimées à la surface cellulaire. Les EPH/EFNs sont impliqués dans de nombreux processus biologiques. L'hypertension artérielle (PA) est une maladie chronique qui, aujourd'hui, est devenue un problème médical critique dans le monde entier et un enjeu de santé publique. La découverte de nouvelles thérapeutiques de l'hypertension sont d'une grande importance pour la santé publique. Jusqu’à tout récemment, il existe seulement quelques études concernant le rôle de l’axe EPH/EFNs sur la fonction des cellules musculaires lisses vasculaires (CMLV). Dans nos études précédentes, nous avons montré qu'EPHB6 et EFNB1, de concert avec les hormones sexuelles, régulent la PA. Dans la présente étude, nous avons constaté que les différents membres de la famille EPH/EFN peuvent réguler soit positivement, soit négativement, la contractilité des CMLV et la PA: tandis que EPHB4 et EFNB2 appartiennent à la première catégorie, EFNB1, EFNB3 et EPHB6 appartiennent à la deuxième. In vivo, des souris males, mais non pas des femelles, porteuses d’une mutation EPHB4 (KO) spécifique du muscle lisse présentent une PA diminuée, comparée aux souris témoins (WT). Les CMLV de souris EPHB4 KO, en présence de testostérone, ont montré une contractilité réduite lors de la stimulation par la phényléphrine (PE). Au niveau moléculaire, la phosphorylation de la protéine kinase II dépendante de Ca2+/calmoduline et de la kinase de la chaine légère de la myosine (CLM) est augmentée, tandis que la phosphorylation de la kinase de la CLM est réduite dans les CMLV KO lors de la stimulation par PE, par rapport au WT CMLV. Cela fournit une base moléculaire à la réduction de la PA et de la contractilité des CMLV chez les souris EPHB4 KO. EFNB2 est le ligand majeur de l’EPHB4. Comme attendu, les souris EFNB2 KO spécifique du muscle lisse avaient un phénotype de PA semblable, quoique non identique, aux souris EPHB4 KO. Les souris mâles EFNB2 KO, mais pas femelles, sous régime régulier ou riche en sel, présentent une PA réduite, par rapport à leurs homologues WT. Au niveau cellulaire, les CMLV des souris KO ont montré une contractilité réduite lors de la stimulation par PE par rapport aux témoins WT. Une région de l’acide aminé (aa) 313 à l’aa 331 dans la partie intracellulaire d’EFNB2 est essentielle pour la signalisation inverse qui régule la contractilité des CMLV, selon des études de mutation-délétion. Dans une étude de génétique humaine, nous avons identifié, dans le gène EFNB2, six SNP qui étaient associées significativement au risque d'hypertension artérielle, de façon dépendante du sexe, ce qui corrobore nos résultats chez les souris. En revanche, la délétion du gène EFNB3 (KO) chez les souris femelles aboutit à une PA élevée et à une augmentation des résistances des petites artères in vivo, améliore la contractilité des petites artères ex-vivo et augmente la contractilité des CMLV in vitro. Les souris mâles KO ont une PA normale, mais la castration conduit à une augmentation significative de la PA dans les souris KO, mais pas dans les souris WT. Les CMLV des souris KO femelles ont montré une phosphorylation accrue de la CLM et une phosphorylation réduite de la kinase de la CLM, ce qui fournit à nouveau une base moléculaire aux phénotypes de PA et de contractilité des CMLV observés. Ce changement de signalisation est attribuable à une protéine adaptatrice Grip1. En effet, dans une étude d'association pan génomique par le Consortium International pour la Pression Sanguine, un SNP dans le gène GRIP1 a approché le seuil de significativité de la valeur p pour son association avec la pression diastolique. Nos recherches, pour la première fois, ont révélé que EPH/EFNs sont de nouveaux composants dans le système de régulation de la PA. Les membres de la famille EPH/EFN peuvent agir comme des forces Yin et Yang pour régler finement le tonus des vaisseaux pour assurer l'homéostasie de la PA et de sa régulation. Ces effets de EPH/EFNs dépendent du sexe et des niveaux d’hormones sexuelles. À partir de ces nouvelles connaissances, nous pourrions développer une nouvelle thérapie personnalisée pour l’hypertension artérielle, utilisant des antagonistes d'hormones sexuelles ou des thérapies de remplacement d'hormones sexuelles, selon les niveaux d'hormones sexuelles des patients et les mutations dans les gènes de l'EPH/EFN.