Curcumin Prevents Renal Damage of l-NAME Induced Hypertension in by Reducing MMP-2 and MMP-9.

In the present study, we investigated whether curcumin administration would interfere with the main renal features of l-NAME-induced hypertension model. For this purpose, we conducted both in vitro and in vivo experiments to evaluate renal indicators of inflammation, oxidative stress, and metalloproteinases (MMPs) expression/activity. Hypertension was induced by l-NAME (70 mg/kg/day), and Wistar rats from both control and hypertensive groups were treated with curcumin (50 or 100 mg/kg/day; gavage) or vehicle for 14 days. Blood and kidneys were collected to determine serum creatinine levels, histological alterations, oxidative stress, MMPs expression and activity, and ED1 expression. l-NAME increased blood pressure, but both doses of curcumin treatment reduced these values. l-NAME treatment increased creatinine levels, glomeruli area, Bowman's space, kidney MMP-2 activity, as well as MMP-9 and ED1 expression, and reduced the number of glomeruli. Curcumin treatment prevented the increase in creatinine levels, MMP-2 activity, and reduced MMP-2, MMP-9, ED1, and superoxide levels, as well as increased superoxide dismutase activity and partially prevented glomeruli alterations. Moreover, curcumin directly inhibited MMP-2 activity in vitro. Thus, our main findings demonstrate that curcumin reduced l-NAME-induced hypertension and renal glomerular alterations, inhibited MMP-2 and MMP-9 expression/activity, and reduced oxidative stress and inflammatory processes, which may indirectly impact hypertension-induced renal outcomes.

Hypertension as predictive factor for bevacizumab-containing first-line therapy in metastatic breast and colorectal cancer in BRECOL (GEICAM/2011-04) study.

BACKGROUND: Retrospective data suggest an association between bevacizumab efficacy and the incidence of arterial hypertension (AHT). Additionally, epigenetic mechanisms have been related to AHT. METHODS: This prospective observational study conducted by GEICAM Spanish Breast Cancer Research Group included metastatic breast (MBC) or colorectal (mCRC) cancer patients treated with bevacizumab-containing chemotherapy as first-line treatment. Blood pressure (BP) levels were measured (conventional and 24-h Holter monitoring) at baseline and up to cycle 3. Primary endpoint assessed BP levels increase as predictive factor for progression-free survival (PFS). Germline DNA methylation profile was explored in pre-treatment blood samples; principal component analysis was used to define an epigenetic predictive score for increased BP levels. RESULTS: From Oct-2012 to Jul-2016, 143 (78 MBC and 65 mCRC) patients were included. The incidence of AHT according to guidelines was neither predictive of PFS nor of best overall tumor response (BOR). No statistically significant association was observed with systolic BP nor diastolic BP increment for PFS or BOR. Grade 3 and 4 adverse events were observed in 37 and 5% of patients, respectively. We identified 27 sites which baseline methylation status was significantly associated to BP levels increase secondary to bevacizumab-containing chemotherapy. CONCLUSIONS: Neither the frequency of AHT nor the increase of BP levels were predictive of efficacy in MBC and mCRC patients treated with bevacizumab-containing chemotherapy. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov Identifier: NCT01733628.

Characterization of Diclofenac-induced Renal Damage in Normotensive and Hypertensive Rats: A Comparative Analysis.

BACKGROUND: Diclofenac is the non-steroidal anti-inflammatory drug (NSAID) mostly prescribed worldwide, but it is highly associated with hypertension and acute kidney injury. Despite that, little information is available about the renal effects of diclofenac in hypertensive individuals, which led us to carry out this comparative study between the renal effects of this NSAID in normotensive (NTR) and spontaneously hypertensive rats (SHR). METHODS: Male Wistar NTR and SHR were orally treated with vehicle (V: 10 mL/kg) or diclofenac sodium (D: 100 mg/kg) once a day for 3 days. Urine volume, electrolytes excretion (Na+, K+, Cl-, and Ca2+), urea, creatinine, pH, and osmolarity were evaluated. Furthermore, blood samples and renal tissue were collected to perform biochemical and histological analysis. RESULTS: Diclofenac increased the renal corpuscle and bowman's space in the SHR, while no microscopic changes were observed in the renal tissue of NTR. Regarding the urinary parameters, diclofenac reduced urine volume, pH, osmolarity, and all electrolytes excretion, followed by decreased urea and creatinine levels in both lineages. Moreover, it also induced hyponatremia, hypokalemia, and hypocalcemia in SHR, while reduced glutathione-S-transferase activity, lipid hydroperoxides, and nitrite levels in renal tissue. CONCLUSIONS: The data presented herein demonstrated that diclofenac induces renal damage and impaired renal function in both NTR and SHR, but those effects are exacerbated in SHR, as seen by the histological changes and electrolytes balance disturbance, therefore, reinforcing that diclofenac may increase the risks of cardiovascular events in hypertensive patients.

Egg white hydrolysate protects white adipose tissue against metabolic insult in deoxycorticosterone acetate-salt rats.

The purpose of this study was to investigate the effect of an egg white hydrolysate (EWH) to protect white adipose tissue damage from cardiometabolic changes induced by severe hypertension. Male Wistar rats were uninephrectomised and divided: SHAM (weekly subcutaneous vehicle (mineral oil + propylene glycol, 1:1)), SHAM + EWH (subcutaneous vehicle plus EWH via gavage, 1 g/kg per day), DOCA (deoxycorticosterone acetate diluted in vehicle subcutaneously weekly in subsequent doses of 20 mg/kg -1st week, 12 mg/kg - 2­3th week, and 6 mg/kg -4­8th week, respectively, plus 1 % NaCl and 0·2 % KCl in drinking water), and DOCA + EWH. Body weight gain, food and water intake, glucose and lipid metabolism were evaluated. Oxidative stress was assessed by biochemical assay and immunofluorescence for NOX-1, nuclear factor kappa B (NFκB), and caspase-3 in retroperitoneal white adipose tissue (rtWAT). Proinflammatory cytokines (IL-6 and 1ß), CD163+ macrophage infiltration, and immunohistochemistry for TNFα and uncoupling protein-1 were evaluated, as well as histological analysis on rtWAT. Glutathione peroxidase and reductase were also determined in plasma. EWH showed hypocholesterolemic, antioxidant, anti-inflammatory, and anti-apoptotic properties in the arterial hypertension DOCA-salt model. The results demonstrated the presence of functional changes in adipose tissue function by a decrease in macrophage infiltration and in the fluorescence intensity of NFκB, NOX-1, and caspase-3. A reduction of proinflammatory cytokines and restoration of antioxidant enzymatic activity and mitochondrial oxidative damage by reducing uncoupling protein-1 fluorescence intensity were also observed. EWH could be used as a potential alternative therapeutic strategy in the treatment of cardiometabolic complications associated with malignant secondary arterial hypertension.

Chemical Characterization of Phoenix dactylifera L. Seeds and their Beneficial Effects on the Vascular Response in Hypertensive Rats.

Although Phoenix dactylifera dates are traditionally consumed for their health benefits, no research has been done on the vascular response in hypertensive animals. This study evaluated the vascular relaxation of hydroalcoholic extracts from seeds of three varieties of P. dactylifera; Sukkari seed (SS), Ajwa seed (AS), and Mabroom seed (MS) on L-NAME-induced hypertension and spontaneously hypertensive rats (SHR). Results showed that all extracts (10 µg/mL) caused relaxations higher than 60% in the aortic rings precontracted with 10- 6 M phenylephrine in normotensive rats, the SS extract was the most potent. Endothelial nitric oxide (NO) pathway is involved as significantly reduced vascular relaxation in denuded-endothelium rat aorta and with an inhibitor (10- 4 M L-Nω-Nitro arginine methyl ester; L-NAME) of endothelial nitric oxide synthase (eNOS). Confocal microscopy confirmed that 10 µg/mL SS extract increases NO generation as detected by DAF-FM fluorescence in intact aortic rings. Consistent with these findings, vascular relaxation in intact aortic rings at 10 µg/mL SS extract was significantly decreased in L-NAME-induced hypertensive rats (endothelial dysfunction model), but not in SHR. In both hypertensive models, the denuded endothelium blunted the vascular relaxation. In conclusion, the hydroalcoholic extract of the seed of P. dactylifera (Sukkari, Ajwa and Mabroom varieties) presents a potent endothelium-dependent vascular relaxation, via NO, in normotensive rats as well as in two different models of hypertension. This effect could be mediated by the presence of phenolic compounds identified by UHPLC-ESI-MS/MS, such as protocatechuic acid, and caftaric acid.

Cadmium induces microcytosis and anisocytosis without anaemia in hypertensive rats.

Dietary cadmium (Cd2+) intake is implicated in the pathogenesis of hypertension and anaemia, but there is a paucity of information on the haematological changes in hypertensive conditions. This study, therefore, aims to evaluate the effects of Cd2+ on blood pressure (BP) and haematological indices in the Sprague-Dawley rat model. Three cohorts (n = 10 each) of control and Cd2+-fed male Sprague-Dawley rats were selected. Cd2+-exposed rats received 2.5 or 5 mg/kg b.w. cadmium chloride via gavage thrice-weekly for eight weeks, while control animals received tap water. BP and flow were measured non-invasively from rat tails twice-weekly using a CODA machine, while weights were measured thrice-weekly. Haematological indices were assessed using the Cell-Dyn Emerald Haematology Analyzer. Data were reported as mean ± SEM, and statistically analyzed using One-Way Analysis of Variance. Bonferroni post hoc test was used for multiple comparisons. Cd2+-exposure induced hypertension by significantly (p < 0.05) elevating systolic, diastolic, and mean arterial BPs, pulse pressure, and heart rate (HR), and increased (p < 0.05) blood flow. Mean cell volume (MCV) and haemoglobin (MCH) were significantly (p < 0.05) reduced, and red cell distribution width (RDW) significantly (p < 0.01) increased by exposure to 5 mg/kg b.w. Cd2+. Haemoglobin concentration (MCHC), haematocrit, haemoglobin, red blood cell, platelet, mean platelet volume, and white blood cell counts were unaffected by Cd2+-exposure. Cd2+ induced hypertension, microcytosis, hypochromicity, and anisocytosis without anaemia, which may be precursor to microcytic anaemia and coronary artery disease. This study is important in Cd2+-exposed environments and warrants further investigations.

Aqueous Fraction from Cucumis sativus Aerial Parts Attenuates Angiotensin II-Induced Endothelial Dysfunction In Vivo by Activating Akt.

BACKGROUND: Endothelial dysfunction (ED) is a marker of vascular damage and a precursor of cardiovascular diseases such as hypertension, which involve inflammation and organ damage. Nitric oxide (NO), produced by eNOS, which is induced by pAKT, plays a crucial role in the function of a healthy endothelium. METHODS: A combination of subfractions SF1 and SF3 (C4) of the aqueous fraction from Cucumis sativus (Cs-Aq) was evaluated to control endothelial dysfunction in vivo and on HMEC-1 cells to assess the involvement of pAkt in vitro. C57BL/6J mice were injected daily with angiotensin II (Ang-II) for 10 weeks. Once hypertension was established, either Cs-AqC4 or losartan was orally administered along with Ang-II for a further 10 weeks. Blood pressure (BP) was measured at weeks 0, 5, 10, 15, and 20. In addition, serum creatinine, inflammatory status (in the kidney), tissue damage, and vascular remodeling (in the liver and aorta) were evaluated. Cs-AqC4 was also tested in vitro on HMEC-1 cells stimulated by Ang-II to assess the involvement of Akt phosphorylation. RESULTS: Cs-AqC4 decreased systolic and diastolic BP, reversed vascular remodeling, decreased IL-1ß and TGF-ß, increased IL-10, and decreased kidney and liver damage. In HMEC-1 cells, AKT phosphorylation and NO production were increased. CONCLUSIONS: Cs-AqC4 controlled inflammation and vascular remodeling, alleviating hypertension; it also improved tissue damage associated with ED, probably via Akt activation.

Effect of Analgesic Low-Dose Ketamine Infusions on the Cardiovascular Response: A Retrospective Analysis.

BACKGROUND: Low-dose ketamine infusion (LDKI) has shown effectiveness for treating acute pain associated with surgical and nonsurgical (traumatic, neuropathic, and acute cancer-related) origin as an adjuvant to opioids. The increasing use of LDKI as an opioid-sparing agent in multimodal analgesia requires a better understanding of its effects on the cardiovascular response, a known dose-dependent side effect of ketamine administration. We investigated the cardiovascular response of acute pain patients treated with LDKI. OBJECTIVES: The aim of the present study was to evaluate the effect of LDKI in hemodynamic variables (blood pressure [BP] and heart rate [HR]) during LDKI analgesia for up to 48 hours of treatment in an acute pain setting. Secondary objectives were to evaluate psychomimetic effects. STUDY DESIGN: Retrospective unicentric cohort design. SETTING: The study was conducted at an academic university hospital. METHODS: We conducted a single-center retrospective cohort analysis of adult patients who underwent LDKI to treat surgical and nonsurgical acute pain. We obtained data from the Hospital San Vicente Fundación Health Documentation System database and evaluated the medical records of 318 patients with surgical and nonsurgical pain. Patients received a 0.1 mg/kg/h ketamine infusion as part of a multimodal analgesic plan. Baseline systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and HR values were compared with those measured after 24 and 48 hours of treatment. Pain level and psychomimetic effects were measured at 24 and 48 hours. Cardiovascular complications and treatment duration were also recorded. Patients with a history of psychiatric, cardiovascular, or cognitive disease were excluded from the study. This study was registered in the clinicaltrials.gov database (identifier: NCT03979105). RESULTS: No statistical differences in SBP, DBP, MAP, or HR were observed when baseline and post-LDKI treatment values were compared (P < 0.05). When comparing hemodynamic variables after exposure to LDKI in patients with and without hypertension, we did not observe statistically significant differences in mean HR, systolic arterial pressure, diastolic arterial pressure, or MAP values at 24 and 48 hours. The frequency of severe pain was reduced from 72% on day 0 to 4.4% on day 1 and 6.2% on day 2 post-LDKI. Observed psychomimetic effects were confusion 4.39%, hallucinations 2.51%, and nightmares 1.25%. No major cardiovascular events were observed. LIMITATIONS: This study was limited by its retrospective design, the lack of a comparative matching cohort, and the good general condition of the majority of patients included in the study. CONCLUSIONS: LDKI (0.1 mg/kg/h) was not associated with significant changes in baseline BP or HR. Our results suggest that as an adjuvant in multimodal analgesia for surgical and nonsurgical acute pain, LDKI has a low impact on the cardiovascular response. KEY WORDS: Ketamine, adverse effects, tachycardia, hypertension, postoperative pain, chronic postsurgical pain.

Role of Brain Endothelin Receptor Type B (ETB) in the Regulation of Tyrosine Hydroxylase in the Olfactory Bulb of DOCA-Salt Hypertensive Rats.

BACKGROUND: We previously reported that endothelins (ETs) regulate tyrosine hydroxylase (TH) activity and expression in the olfactory bulb (OB) of normotensive and hypertensive animals. Applying an ET receptor type A (ETA) antagonist to the brain suggested that endogenous ETs bind to ET receptor type B (ETB) to elicit effects. OBJECTIVE: The aim of the present work was to evaluate the role of central ETB stimulation on the regulation of blood pressure (BP) and the catecholaminergic system in the OB of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. METHODS: DOCA-salt hypertensive rats were infused for 7 days with cerebrospinal fluid or IRL-1620 (ETB receptor agonist) through a cannula placed in the lateral brain ventricle. Systolic BP (SBP) and heart rate were recorded by plethysmography. The expression of TH and its phosphorylated forms in the OB were determined by immunoblotting, TH activity by a radioenzymatic assay, and TH mRNA by quantitative real-time polymerase chain reaction. RESULTS: Chronic administration of IRL-1620 decreased SBP in hypertensive rats but not in normotensive animals. Furthermore, the blockade of ETB receptors also decreased TH-mRNA in DOCA-salt rats, but it did not modify TH activity or protein expression. CONCLUSION: These findings suggest that brain ETs through the activation of ETB receptors contribute to SBP regulation in DOCA-salt hypertension. However, the catecholaminergic system in the OB does not appear to be conclusively involved although mRNA TH was reduced. Present and previous findings suggest that in this salt-sensitive animal model of hypertension, the OB contributes to chronic BP elevation.

Antihypertensive medication class and diastolic orthostatic hypertension in older Caribbean adult patients.

In the Caribbean there is limited data on orthostatic hypertension (OHT) in elderly hypertensive patients with atherosclerotic disease who are at risk for cardiovascular events. The authors examined the association of antihypertensive classes of drugs with diastolic OHT in patients 60 year and older with hypertension and hyperlipidemia attending public primary care facilities. These relationships were evaluated in a cross-sectional study of hypertensive hyperlipidemic older patients (n = 400) to determine orthostatic changes in blood pressure based on seated to standing measurements. OHT was defined as an increase in systolic blood pressure of ≥20 mm Hg and/or increase in diastolic blood pressure of ≥10 mm Hg upon orthostasis at 3 min. Patients were categorized based on their orthostatic blood pressure response: orthostatic normotensive (n = 200) and blood pressure dysregulated (n = 200) of which 168 were diastolic OHT. Multivariable logistic regression models were used to examine associations of antihypertensive classes and diastolic OHT. Renin-angiotensin-aldosterone-system (RAAS) blockers were the most commonly prescribed (79.3%), followed by diuretics (DIUs) (61.6%), dihydropyridine calcium channel blockers (dCCBs) (53.8%), and beta-blockers (BBs) (19.3%). Most normotensive (76.0%) and diastolic OHT (75.0%) patients were prescribed two or more antihypertensive medications. Pharmaceutical prescription of triple combination RAAS blockers + dCCBs + DIUs (OR, 0.55; 95% CI, 0.31-0.99) or RAAS blockers + dCCBs + BBs (OR, 0.23; 95% CI, 0.06-0.92) showed a protective effect of diastolic OHT in analyses adjusted for age, sex, sitting diastolic blood pressure, and comorbidities. Our study suggests prescription of triple combination antihypertensive drugs of RAAS blockers + dCCBs + DIUs or RAAS blockers + dCCBs + BBs may reduce the likelihood of diastolic OHT.

Sildenafil attenuates oxidative stress and endothelial dysfunction in lead-induced hypertension.

Lead (Pb) reduces NO bioavailability, impairs the antioxidant system, and increases the generation of reactive oxygen species (ROS). Pb-induced oxidative stress may be responsible for the associated endothelial dysfunction. Sildenafil has shown nitric oxide (NO)-independent action, including antioxidant effects. Therefore, we examined the effects of sildenafil on oxidative stress, reductions of NO and endothelial dysfunction in Pb-induced hypertension. Wistar rats were distributed into three groups: Pb, Pb + sildenafil and Sham. Blood pressure and endothelium-dependent vascular function were recorded. We also examined biochemical determinants of lipid peroxidation and antioxidant function. ROS levels, NO metabolites and NO levels in human umbilical vein endothelial cells (HUVECs) were also evaluated. Sildenafil prevents impairment of endothelium-dependent NO-mediated vasodilation and attenuates Pb-induced hypertension, reduces ROS formation, enhances superoxide dismutase (SOD) activity and antioxidant capacity in plasma and increases NO metabolites in plasma and HUVECs culture supernatants, while no changes were found on measurement of NO released from HUVECs incubated with plasma of the Pb and Pb + sildenafil groups compared with the sham group. In conclusion, sildenafil protects against ROS-mediated inactivation of NO, thus preventing endothelial dysfunction and attenuating Pb-induced hypertension, possibly through antioxidant effects.

Mineralocorticoid receptors contribute to ethanol-induced vascular hypercontractility through reactive oxygen species generation and up-regulation of cyclooxygenase 2.

The effects on blood pressure produced byethanol consumption include both vasoconstriction and activation of the renin-angiotensin-aldosterone system (RAAS), although the detailed relationship between these processes is yet to be accomplished. Here, we sought to investigate the contribution of mineralocorticoid receptors (MR) to ethanol-induced hypertension and vascular hypercontractility. We analyzed blood pressure and vascular function of male Wistar Hannover rats treated with ethanol for five weeks. The contribution of the MR pathway to the cardiovascular effects of ethanol was evaluated with potassium canrenoate, a MR antagonist (MRA). Blockade of MR prevented ethanol-induced hypertension and hypercontractility of endothelium-intact and -denuded aortic rings. Ethanol up-regulated cyclooxygenase (COX)2 and augmented vascular levels of both reactive oxygen species (ROS) and thromboxane (TX)B2, a stable metabolite of TXA2. These responses were abrogated by MR blockade. Hyperreactivity to phenylephrine induced by ethanol consumption was reversed by tiron [a scavenger of superoxide (O2∙-)], SC236 (a selective COX2 inhibitor) or SQ29548 (an antagonist of TP receptors). Treatment with the antioxidant apocynin prevented the vascular hypercontractility, as well as the increases in COX2 expression and TXA2 production induced by ethanol consumption. Our study has identified novel mechanisms through which ethanol consumption promotes its deleterious effects in the cardiovascular system. We provided evidence for a role of MR in the vascular hypercontractility and hypertension associated with ethanol consumption. The MR pathway triggers vascular hypercontractility through ROS generation, up-regulation of COX2 and overproduction of TXA2, which will ultimately induce vascular contraction.

Maintenance of angiogenesis inhibition with aflibercept after progression to bevacizumab in metastatic colorectal cancer: real life study in the Valencian community.

INTRODUCTION: The second-line chemotherapy in metastatic colorectal cancer (mCRC) with FOLFIRI-aflibercept demonstrated an increase in survival compared with FOLFIRI in patients previously treated with oxaliplatin-based regimens. Few data are available in patients treated previously with bevacizumab. Our objective is to evaluate the efficacy and safety of FOLFIRI-aflibercept in second-line treatment in patients who have previously received bevacizumab. PATIENTS AND METHODS: This is a observational, retrospective study of patients with mCRC treated with FOLFIRI-aflibercept in 2nd line in eight hospitals in the Valencian Community. Survival, response, and toxicity were analyzed. RESULTS: 122 patients with a median age of 61 years were included. 89% of patients had PS 0-1. The median of PFS (progression free survival) and OS (overall survival) was 5.45 (95% CI 4.74-6.15 months) and 10.15 (95% CI 7.47-12.82 months), respectively. Disease control rate 59.8%. The most common grade 3-4 adverse events were neutropenia (13,1%) and asthenia (9%). The presence of hypertension during treatment with FOLFIRI-aflibercept was associated with a survival benefit. Median of OS was 14.45 (95% CI 11.58-17.32) in patients with hypertension vs 7.78 (95% CI 5.02-10.54) in patients without hypertension (p = .001). Our results suggest that the presence of PS 0, primary tumor surgery, metachronous metastases, and the presence of only 1 metastatic location, are favorable prognostic factors associated with better OS. CONCLUSIONS: Our results confirm the value of maintaining angiogenesis inhibition with FOLFIRI-aflibercept in mCRC after progression to a first-line treatment with bevacizumab. The development of hypertension during treatment is a possible predictive marker of response.

Estimation of the economic benefits for the public health system related to salt reduction in Costa Rica.

Excessive salt and sodium intake are strongly associated with high blood pressure and increased risk of cardiovascular disease. High blood pressure in turn is the main risk factor for the global burden of morbidity and mortality. The prevalence of this disease in the adult population of Costa Rica in 2018 was 37.2%. Costa Rica has limited information on the economic costs for the public health system and related of the prevalence of this type of disease mediated by dietary factors such as salt intake. OBJECTIVE: to estimate the economic benefits for the public health system related to salt reduction in Costa Rica for the year 2018. METHODOLOGY: estimation of the economic benefits for the public healthcare costs and productivity losses associated to reducing the per capita salt consumption of Costa Ricans to 5g/day, including the estimation of the Years of Life Productive Lost and of the direct costs on consultations, hospitalizations, and medications for the Costa Rica Social Security System. RESULTS: The total annual costs of hospitalization, consultations, and medications attributable to excessive salt intake in the population older than 15 years of age for the year 2018, were estimated at USD $15.1 million. The highest were in hospitalizations (53%), followed by consultations and medications (32% and 15%, respectively). CONCLUSION: NCDs caused by excessive salt intake represent important economic losses for the country, not only in terms of direct health costs, but also indirect due to the increase in years of potential life lost due to premature deaths because of CVD, which causes significant losses of human capital and, therefore, to the economy and the development of Costa Rica.

Oxidative Stress Induced by 30 Days of Mercury Exposure Accelerates Hypertension Development in Prehypertensive Young SHRs.

Mercury is considered a risk factor for the development of hypertension and other cardiovascular diseases. We investigated whether the effects of mercury exposure on haemodynamic parameters of young Wistar rats and prehypertensive SHRs might alter the time course of hypertension development. Young (4 weeks) male Wistar rats and SHRs were randomly assigned to four groups: untreated Wistar rats (Wistar Ct), Wistar rats exposed to mercury chloride for 30 days (Wistar Hg), untreated SHRs (SHR Ct) and SHRs exposed to mercury chloride (SHR Hg) for 30 days. Non-invasive and invasive arterial pressures were measured to investigate pressure reactivity; nitrite/nitrate levels, ACE activity, and lipid peroxidation were measured in plasma. The systolic blood pressure (SBP) of the Wistar rat groups did not change but increased in the SHRs from the second week to the last week. Hg exposure accelerated the increase in the SBP of SHRs. L-NAME administration increased SBP and diastolic blood pressure (DBP) in all groups, but this increase was smaller in SHRs exposed to Hg. A decrease in plasma nitrite and nitrate levels in the SHR Hg group suggested that mercury reduced NO bioavailability. Tempol-reduced blood pressure suggesting that the superoxide anion played a role in the marked increase in this parameter. These findings provide evidence that Hg exposure might activate mechanisms to accelerate hypertension development, including a reduction in NO bioavailability. Therefore, predisposed individuals under mercury exposure are at greater risk from an enhanced development of hypertension.

Small conductance calcium-activated potassium channels and nitric oxide/cGMP pathway mediate cardioprotective effects of Croton urucurana Baill. In hypertensive rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Croton urucurana Baill. (Euphorbiaceae), popularly known as 'sangue de dragão' is a Brazilian species widely used in traditional medicine for cardiovascular ailments. AIM: To investigate the cardiovascular effects of the C. urucurana extract in spontaneously hypertensive rats (SHRs). MATERIALS AND METHODS: Leaves from C. urucurana were collected and morphoanatomically characterized. The ethanol-soluble fraction (ESCU) was obtained and analyzed by LC-DAD-MS. Using female Wistar rats we investigated the acute toxicity of ESCU. Then, SHRs (six months old) received vehicle, hydrochlorothiazide (25 mg/kg), or ESCU (30, 100, 300 mg/kg) for 28 days. At the beginning and at the end of treatments, urine samples were obtained to assess renal function. At the end of the trial period, the blood pressure, mesenteric vascular beds (MVBs) reactivity, and electrocardiographic profile were evaluated. Serum angiotensin-converting enzyme activity, as well as urea, creatinine, sodium, potassium, nitrite, malondialdehyde, nitrotyrosine, and aldosterone levels were determined. Relative organ weights and histopathological analysis were performed. Finally, the cardiac function on a Langendorff system, as well as the molecular mechanisms involved in the vasodilator effects of ESCU in MVBs were also investigated. RESULTS: The compounds annotated from ESCU by LC-DAD-MS included mainly phenylpropanoid derivatives, alkaloids, O-glycosylated megastigmanes, glycosylated flavonoids, flavan-3-ols, and others, such as quercetin O-deoxyhexosyl-hexoside, magnoflorine, reticuline, and taspine. None of the animals showed any signs of toxicity. Male SHRs treated only with the vehicle showed important cardiovascular changes, including a reduction in renal function, increase in serum oxidative stress, and hemodynamic, electrocardiographic, and morphological changes typical of hypertensive disease. Moreover, parameters of cardiac function, including left ventricular developed pressure, peak rate of contraction, peak rate of relaxation, and the rate pressure product were significantly altered, showing a significant impairment of ventricular function. All ESCU-doses presented a significant cardioprotective effect in SHRs rats. The 28-day treatment normalized the hemodynamic, electrocardiographic, morphological, and renal impairments, as well as reversed the changes in ventricular function induced by hypertension. In MVBs with an intact endothelium, ESCU (0.1, 0.3, and 1 mg) dose-dependently induced vasodilation. Endothelium removal or the inhibition of nitric oxide synthase prevented the vasodilatory effect of ESCU. Perfusion with a physiological saline solution that contained KCl, tetraethylammonium, or apamin also abolished the vasodilatory effect of ESCU. CONCLUSION: Prolonged ESCU-treatment showed significant cardioprotective effects in SHRs. Moreover, the data showed the role of nitric oxide and calcium-activated small conductance potassium channels in the cardiovascular effects of ESCU.

Chronic cyclooxygenase-2 inhibition prevents the worsening of hypertension and endothelial dysfunction induced by ouabain in resistance arteries of spontaneously hypertensive rats.

AIM: Previous studies raise cyclooxygenase (COX) activation as a possible mechanism involved in the pathophysiology of ouabain-induced hypertension. We hypothesized that inhibition of COX-2 activity might prevent ouabain-induced vascular dysfunction and worsening of hypertension in spontaneously hypertensive rats (SHR). METHODS: SHR were exposed to ouabain or vehicle and treated or not with the selective COX-2 inhibitor nimesulide for 5 weeks. Systolic blood pressure was measured by plethysmography. Vascular reactivity by wire myograph and protein expression by Western-blot were assessed in mesenteric resistance arteries (MRA) of groups. Thromboxane A2 (TXA2) production by ELISA was evaluated in MRA supernatants of groups. RESULTS: Noradrenaline-induced maximal contraction (Emax) was greater in MRA from SHR receiving ouabain than those of vehicle group. In situ inhibition of COX-2, TXA2 synthase, or TP receptor reduced the Emax to noradrenaline in MRA of ouabain to vehicle levels. TXA2 production was higher in ouabain than in vehicle group. Ouabain enhanced expression of cytoplasmic tyrosine kinase Src (c-Src)/ERK1/2/COX-2/TXA2 synthase/TP receptor in SHR MRA, but did not change NFkB/iKB ratio. Anticontractile effect of nitric oxide (NO) was smaller in MRA from ouabain- than vehicle-treated SHR, as well as eNOS and nNOS expression. Nimesulide co-treatment prevented the ouabain-induced worsening of hypertension and noradrenaline MRA hypercontractility in SHR. CONCLUSION: Ouabain worsen hypertension and induce MRA hypercontractility in SHR associated with upregulated c-Src/ERK1/2/COX-2/TXA2 synthase/TXA2/TP receptor axis. These effects were prevented by COX-2 inhibition.

Cadmium-induced hypertension is associated with renal myosin light chain phosphatase inhibition via increased T697 phosphorylation and p44 mitogen-activated protein kinase levels.

Dietary intake of the heavy metal cadmium (Cd2+) is implicated in hypertension, but potassium supplementation reportedly mitigates hypertension. This study aims to elucidate the hypertensive mechanism of Cd2+. Vascular reactivity and protein expression were assessed in Cd2+-exposed rats for 8 weeks to determine the calcium-handling effect of Cd2+ and the possible signaling pathways and mechanisms involved. Cd2+ induced hypertension in vivo by significantly (p < 0.001) elevating systolic blood pressure (160 ± 2 and 155 ± 1 vs 120 ± 1 mm Hg), diastolic blood pressure (119 ± 2 and 110 ± 1 vs 81 ± 1 mm Hg), and mean arterial pressure (133 ± 2 and 125 ± 1 vs 94 ± 1 mm Hg) (SBP, DBP, and MAP, respectively), while potassium supplementation protected against elevation of these parameters. The mechanism involved augmentation of the phosphorylation of renal myosin light chain phosphatase targeting subunit 1 (MYPT1) at threonine 697 (T697) (2.58 ± 0.36 vs 1 ± 0) and the expression of p44 mitogen-activated protein kinase (MAPK) (1.78 ± 0.20 vs 1 ± 0). While acetylcholine (ACh)-induced relaxation was unaffected, 5 mg/kg b.w. Cd2+ significantly (p < 0.001) attenuated phenylephrine (Phe)-induced contraction of the aorta, and 2.5 mg/kg b.w. Cd2+ significantly (p < 0.05) augmented sodium nitroprusside (SNP)-induced relaxation of the aorta. These results support the vital role of the kidney in regulating blood pressure changes after Cd2+ exposure, which may be a key drug target for hypertension management. Given the differential response to Cd2+, it is apparent that its hypertensive effects could be mediated by myosin light chain phosphatase (MLCP) inhibition via phosphorylation of renal MYPT1-T697 and p44 MAPK. Further investigation of small arteries and the Rho-kinase/MYPT1 interaction is recommended.

Lead and mercury 28 day exposure at small concentrations reduces smooth muscle relaxation by decreasing cGMP.

Cardiovascular diseases are among the main causes of mortality in the world. There is evidence of cardiovascular harm after exposure to low lead or mercury concentrations, but the effects of chronic exposure to the association of low doses of these toxic metals are still unknown. This work evaluated after 4 weeks, the association effects of low concentrations of lead and mercury on blood pressure and vascular resistance reactivity. Wistar rats were exposed for 28 days to lead acetate (1st dose of 4 µg/100 g and subsequent doses of 0.05 µg /100 g/day to cover daily losses) and mercury chloride (1st dose of 2.17 µg/kg and subsequent doses of 0.03 µg/kg/ day to cover daily losses) and the control group received saline, i.m. Results showed that treatment increased blood pressure and induced left ventricular hypertrophy. The mesenteric vascular reactivity to phenylephrine and the endothelium-dependent vasodilator response assessed by acetylcholine did not change. Additionally, reduced involvement of vasoconstrictor prostanoids derived from cyclooxygenase was observed in the PbHg group. By other regulatory routes, such as potassium channels, the vessel showed a greater participation of BKCa channels, and a reduction in the participation of Kv channels and SKCa channels. The endothelium-independent smooth muscle relaxation was significantly impaired by reducing cGMP, possibly through the hyperstimulation of Phosphodiesterase-5 (PDE5). Our results suggested that exposure to low doses of lead and mercury triggers this compensatory mechanism, in response to the augment of arterial pressure.

Central endothelin ETB receptor activation reduces blood pressure and catecholaminergic activity in the olfactory bulb of deoxycorticosterone acetate-salt hypertensive rats.

Endothelins regulate catecholaminergic activity in the olfactory bulb (OB) in normotensive and hypertensive animals. Administration of an endothelin ETA receptor antagonist decreases blood pressure in deoxycorticosterone acetate-salt (DOCA-salt) rats along with a reduction in tyrosine hydroxylase (TH) activity and expression. In the present work, we sought to establish the role of brain endothelin ETB receptor on blood pressure regulation and its relationship with the catecholaminergic system within the OB of DOCA-Salt rats. Sprague-Dawley male rats were divided into control and DOCA-Salt groups. Blood pressure, heart rate and TH activity as well as neuronal nitric oxide synthase (nNOS) expression were assessed following IRL-1620 (selective endothelin ETB receptor agonist) applied to be brain. IRL-1620 significantly reduced systolic, diastolic, and mean arterial pressure in DOCA-Salt hypertensive rats. It also decreased TH activity, TH total and phosphorylated forms expression as well as its mRNA in the OB of hypertensive animals. The expression of phospho-Ser1417-nNOS, which reflects nNOS activation, was significantly decreased in the of OB of DOCA-salt rats, but it was enhanced by IRL-1620. These findings suggest that DOCA-Salt hypertension depends on endogenous central endothelin ETA receptor activity, rather than on ETB, and that low endothelin ETB stimulation is essential for blood pressure elevation in this animal model. The effect of endothelin ETA receptor antagonism may also result from endothelin ETB receptor overstimulation. The present study shows that endothelin receptors are involved in the regulation of TH in the OB and that such changes are likely implicated in the hemodynamic control and sympathetic outflow.