Na+ sensitive hypertension in Dahl salt sensitive rats (Dahl S) or spontaneously hypertensive rats (SHR) is linked to intrinsic changes in the brain that favour increased Na+ entry into the cerebrospinal fluid (CSF) followed by increases in sympathetic hyperactivity and hypertension (Huang et al 2004). Similar responses are observed in salt resistant and Wistar rats that receive an intracerebroventricular (icv) infusion of Na+ rich artificial cerebrospinal fluid (aCSF) (Huang et al 2001, 2006). Downstream to increased CSF[Na+], a pathway has been described involving mineralocorticoid receptors (MRs), benzamil sensitive Na+ channels, “ouabain”, and angiotensin II type 1 receptors (AT1-R) (Huang et al 1998, Zhao et al 2001, Wang and Leenen 2003, Huang et al 2008). Blood pressure (BP) responses to increased CSF[Na+] may involve activation of AT1-R in the subfornical organ (SFO) as the BP response to injection of NaCl into a lateral ventricle can be blocked by AT1-R blockade in the SFO (Rohmeiss et al 1995a). The role of aldosterone and AT1-R in the SFO was investigated in mediating the BP and heart rate (HR) response to increases in CSF[Na+] and local [Na+]. Results show that infusion of 0.45M and 0.6M Na+ rich aCSF into the SFO increases BP but not HR. The BP is unchanged by infusion of a mannitol solution osmotically equivalent to 0.6M Na+ rich aCSF indicating that the SFO is Na+ sensitive. The BP response to a lower concentration of Na+ (0.45M) is enhanced by prior infusion of aldosterone while BP response to 0.6M is not further enhanced suggesting that the SFO may have maximal responsiveness to acute increases in [Na+] at 0.6M. The BP responses to Na+ rich aCSF in the SFO and the enhancement of those responses by aldosterone can be blocked by infusion of the AT1-R blocker Candesartan in the SFO. This response appears therefore to be mediated in the SFO through AT1-R activation, likely through Ang II release in the SFO. ICV infusion of Na+ rich aCSF increases BP but not HR and this response is partially blocked by infusion of the AT1-R blocker Candesartan in the SFO. This indicates that nearly half the BP responses to icv infusion of Na+ rich aCSF is mediated through AT1-R activation in the SFO. Lastly, contrary to icv, PVN and MnPO studies (Huang and Leenen 1996, Budzikowski and Leenen 2001, Gabor and Leenen 2009) ouabain in the SFO does not increase BP or HR. In conclusion, these results show that the SFO is Na+ sensitive and mediates half the BP responses to changes in CSF[Na+] through a mechanism that involves AT1-R activation. The SFO is further sensitized to Na+ by aldosterone presumably through its genomic effects. Lastly, ouabain in the SFO does not increase BP or HR suggesting that endogenous ouabain in the SFO is not involved in modulating BP or HR responses.

The mechanisms mediating the hypertension of preeclampsia (PE) are unclear. Endogenous digitalis-like factors (EDLFs) are specific sodium pump (SP) inhibitors implicated in essential and experimental hypertension, but they have not been fully explored in the setting of PE. This study uses a digoxin antibody Fab fragment to address the question of whether such factors are present and increased in PE, to investigate a possible treatment of PE, and to isolate and characterize all EDLFs present in PE. Sera and placenta from women with PE did show a significant increase in SP inhibition in comparison to women with normal pregnancy and Digibind® was found to bind EDLFs and essentially block or reverse SP inhibition. Sera were collected in a Phase II, double-blind, placebo controlled clinical study in which women with severe preeclampsia were dosed with Digibind®, as a therapeutic, and the SP activity measured. Sera and placenta from women with PE was also investigated for their inhibitory effects on the SP. Known candidates for EDLFs were investigated for their SP inhibitory effects, as well as how digitalis antibody immune Fab fragments, Digibind® and DigiFab™, bound them and affected the SP activity. Digibind® is also a sufficient affinity material used to isolate and purify PE EDLFs. Additionally, the placentas of preeclamptic women have high levels of similar EDLFs. These studies provide evidence for the existence of EDLFs that circulate in women with PE, and Digibind® is an effective and novel tool to bind, isolate and purify EDLFs in PE.

No description available.

No description available.

Calcium, a pivotal ion in various human signaling pathways, holds significant relevance in cancer research and treatment. Investigating the transmission of spontaneous calcium signals between cells and understanding how they are influenced by different treatments is therefore an interesting area of study. This master's thesis presents a newly developed tool designed for analyzing intracellular calcium concentration [Ca2+] fluctuations. The tool encompasses a cell segmentation model, tracking algorithms, nearest neighbor identification, mean intensity measurement, and calculations of dominant frequency of [Ca2+] oscillations and signal correlation among neighboring cells. The tool was applied to fluorescence microscopy images of Madin-Darby Canine Kidney II cells expressing GCaMP6m and either treated with the cardiac glycoside ouabain, a combination of ouabain and the gap junction blocker heptanol, or left untreated for comparison. Additionally, an exploration into the impact of connexin 43 (Cx43) transfection on [Ca2+] fluctuations was undertaken. The transfection rate for Cx43 did not reach a sufficient level, impeding a thorough analysis of its influence on [Ca2+] fluctuations. Furthermore, the investigation into dominant frequencies and signal correlation did not yield conclusive findings regarding the effects of ouabain and heptanol. Nevertheless, a foundational tool for analysis has been developed, with the potential for expansion to analyze more aspects calcium signaling and application to additional cell types and treatments. / Kalcium, en central jon i olika signalvägar hos människan, spelar en viktig roll inom cancerforskning och -behandling. Att undersöka överföringen av spontana kalciumsignaler mellan celler och förstå hur dessa påverkas av olika behandlingar är därav ett intressant studieområde. I denna masteruppsats presenteras ett nyutvecklat verktyg utformat för att analysera variationer i intracellulär kalciumkoncentration [Ca2+] . Verktyget omfattar en cellsegmenteringsmodell, spårningsalgoritmer, identifiering av närmaste grannar, medelintensitetsmätning, beräkningar av dominant frekvens för oscillationer i [Ca2+] samt korrelation i dessa variationer mellan närliggande celler. Verktyget tillämpades på fluorescensmikroskopibilder av Madin-Darby Canine Kidney II-celler som uttryckte GCaMP6m och antingen hade behandlats med hjärtglykosiden ouabain, en kombination av ouabain och gap junction-blockeraren heptanol eller lämnats obehandlade för jämförelse. Dessutom undersöktes hur variationerna i [Ca2+] påverkades om cellerna transfekterades med konnexin 43 (Cx43). Andelen celler per prov som genomgick lyckad transfektion av Cx43 nådde aldrig upp till önskade nivåer, vilket förhindrade närmare analys av påverkan på [Ca2+]. Undersökningen av dominanta frekvenser och korrelation i signaler gav inte heller några entydiga svar på hur ouabain och heptanol påverkar [Ca2+]. Likväl har ett grundläggande verktyg för analys utvecklas, som har potential att utvidgas till analys av fler aspekter av kalciumsignalering och tillämpning på fler celltyper och behandlingar.

Ouabain and other cardiotonic steroids are known to inhibit Na + ,K + -ATPase (NKA), theion pump responsible for the ionic gradient across the plasma membrane. These steroidsdisplay a selective toxicity towards several tumour cells in comparison to primary humancells, however, the mechanism behind this is not yet understood. Here, we examined theouabain toxicity in renal epithelial cells, proximal tubular cells (PTCs) of different origin. Weinvestigated the relative cytotoxicity in cancer cells (A-498) and papilloma virus-transformedPTCs (HK-2) as well as to primary human PTCs (hPTC) to validate key components in theeffect. In exposure to ouabain, we examined the cell viability and density by MTT and CrystalViolet assays, and cell migration by a scratch assay. The cytotoxic effect was also studied invarious pH, glucose and potassium ion concentrations. In addition, apoptosis was examinedby the TUNEL assay, and if ouabain kills cancer cells through activation of thevolume-regulated anion channel VRAC channel via NKA. We found that there is a decrease in viable cells when cells are exposed to ouabain ≥ 10nM, however, the effect was not seen to be selective towards cancer cells, nor due toapoptosis and the activation of VRAC. The cytotoxic effect was greater in more acidicextracellular pH ~6.8, but independent of glucose concentration in the medium. Interestingly,the effect was also reversed at an increased extracellular concentration of potassium, andouabain did selectively inhibit the cancer cells to migrate. Thus, there could be potential forouabain to act as an anti-cancer agent for renal cancer and to inhibit tumour metastasization. / Ouabain och andra kardiotoniska steroider är kända för att inhibera Na + ,K + -ATPas (NKA),membranpumpen som är ansvarig för den aktiva jontransporten av natrium och kalium ochjongradienten över plasmamembranet. De har påvisat en selektiv toxicitet mot vissatumörceller i jämförelse med primära humana celler, men det är dock inte förstått hurmekanismen bakom denna företeelse fungerar. I denna studien undersökte vi ouabainstoxicitet i njurcancerceller (A-498) och papillomavirustransformerade proximala tubuliceller(hPTC) för att identifiera effektens nyckelkomponenter. Vid exponering av ouabain undersökte vi cellviabiliteten och -densiteten genom MTT- ochkristallviolett-analyser, samt cellmigrering genom scratch-analys. Den cytotoxiska effektenstuderades också under olika pH-förhållanden samt glukos- och kaliumkoncentrationer.Dessutom undersöktes det om apoptos orsakar celldöd genom TUNEL-analys, och omouabain dödar njurcancerceller genom aktivering av den volymreglerade anjonkanalen(VRAC) via NKA. Vi fann minskning av cellernas livskraft vid exponering av ≥ 10 nM ouabain, men effektentycktes dock inte se ut att vara selektiv gentemot cancerceller, inte heller på grund av apoptosoch aktivering av VRAC. Den cytotoxiska effekten var större vid lägre pH, men oberoendeav mediets glukoskoncentrationen. Intressant nog motverkades också effekten vid förhöjdkoncentration av kaliumjoner, och ouabain hämmade selektivt cancercellerna att migrera.Således finns det en viss potential för ouabain att kunna fungera som ett anticancermedel motnjurcancer och att hämma metastasutveckling.

High salt intake contributes to the development of hypertension in salt-sensitive humans and animals and the mechanistic causes are poorly understood. In Dahl salt-sensitive (S) but not salt-resistant (R) rats, high salt diet increases cerebrospinal fluid (CSF) [Na+] and activates an aldosterone-mineralocorticoid receptor-epithelial sodium channel-endogenous ouabain (MR-ENaC-EO) neuromodulatory pathway in the brain that enhances the activity of sympatho-excitatory angiotensinergic and glutamatergic pathways, leading to an increase in sympathetic nerve activity (SNA) and blood pressure (BP). We hypothesize that high salt diet in Dahl S rats enhances Ang II release in the paraventricular nucleus (PVN), causing a decrease in local nitric oxide (NO) action and an increase in local glutamate release thereby elevating SNA, BP and heart rate (HR). The present study evaluated the effects of agonists or blockers of MR, ENaC, EO, nitric oxide synthase (NOS) or glutamate and AT1-receptors on the BP and HR responses to acute infusions of Na+ rich aCSF, intracerebroventricularly (icv), or in the PVN of Dahl S, R or Wistar rats or to high salt diet in Dahl S and R rats. In Wistar rats, aldosterone in the PVN enhanced the BP and HR responses to infusion of Na+ rich aCSF in the PVN, but not in the CSF, and only the enhancement was prevented by blockers of MR, ENaC and EO in the PVN. AT1-receptor blockers in the PVN fully blocked the enhancement by aldosterone and the responses to infusion of Na+ rich aCSF icv, or in the PVN. Na+ rich aCSF in the PVN caused larger increases in BP and HR in Dahl S vs. R rats and the responses to Na+ were fully blocked by an AT1-receptor blocker in the PVN. BP and HR responses to a NOS blocker in the PVN were the same, but L-NAME enhanced Na+ effects more in Dahl R than S rats. High salt diet attenuated increases in BP from L-NAME in the PVN of Dahl S but not R rats. AT1 and glutamate receptor blockers candesartan and kynurenate in the PVN decreased BP in Dahl S but not R rats on high salt diet. At the peak BP response to candesartan, kynurenate in the PVN further decreased BP whereas candesartan did not further decrease BP at the peak BP response to kynurenate. Our findings indicate that both an acute increase in CSF [Na+] and high salt intake in Dahl S rats increases AT1-receptor activation and decreases NO action in the PVN thereby contributing to the pressor responses to Na+ and presumably, to dietary salt-induced hypertension. The increased BP response to AT1-receptor activation in the PVN of Dahl S is mediated by enhanced local glutamate receptor activation. An MR-ENaC-EO pathway in the PVN can be functionally active and further studies need to assess its role in Dahl S rats on high salt intake.

Na,K-ATPase é uma proteína de membrana que tem como função manter o equilíbrio osmótico nas células pela hidrólise de ATP. A ouabaína (OUA) se liga a Na,K-ATPase e é capaz de ativar cascatas de sinalização. As subunidades a da Na,K-ATPase possuem 4 isoformas que são distribuídas de forma diferenciada nos tecidos. As células da glia são importantes na resposta contra lesões no cérebro e também controlam a inflamação. Dados na literatura mostram que a OUA tem efeito protetor em alguns tipos de dano. O objetivo do estudo é avaliar a função da isoforma a2 na cultura de células da glia em resposta à OUA e ao LPS. Nós investigamos a ação da OUA em diversas concentrações e LPS (1g/mL) na viabilidade celular (LDH) e proliferação celular (MTT). O LPS foi utilizado como modelo de inflamação e uma das perguntas era se o tratamento prévio com OUA, seria capaz de reverter a ativação do fator de transcrição NF-kB que está envolvido com inflamação. O pré-tratamento com OUA diminuiu a ativação do NF-kB induzida pelo LPS. Após, nós silenciamos a isoforma a2 das células da glia com RNAi. Os nossos dados mostram que o pré-tratamento com OUA reverte o efeito na ativação do NF-kB causado pelo LPS. Provavelmente, a isoforma a2 está relacionada com alguma via de sinalização que interage com a via do LPS. / Na,K-ATPase is a conserved membrane protein which maintains the osmotic balance in the cell by the hydrolysis of ATP. Ouabain (OUA) binds to Na,K-ATPase and it can activate signaling pathways. The a subunits of Na,K-ATPase have 4 isoforms which are distributed in a different pattern in the tissues. Glial cells have an important role in the response against injury and they also control inflammation. Some data have reported that OUA can protect against some types of injury. The aim of this study is to evaluate the role of a2 isoform in glial cells in response to OUA and LPS stimulus. We investigated the action of OUA and LPS in cell viability (LDH) and cell proliferation (MTT). LPS was used as a model of inflammation and one of our questions was if the treatment with OUA before LPS was capable of reduce the activation of the transcription factor NF-kB which is involved in inflammation. The pre-treatment with OUA decreased the NF-kB activation induced by LPS. We also silenced the a2 isoform in culture glial cells with iRNA. Taken together our data showed that OUA pretreatment reversed the NF-kB activation induced by LPS in primary cultures of glial cells from mice. Probably,the a2 isoform is related with some signaling pathway that interacts with the LPS pathway.

Inibidores da Na+/K+ ATPase, como a ouabaína (OUA), estão associados à gênese/manutenção da hipertensão arterial (HA). Ratos tratados com OUA ficam hipertensos e suas artérias mesentéricas de resistência (AMR) apresentam disfunção vascular, estresse oxidativo e remodelamento estrutural e mecânico. Modelos de HA dependente de volume, como o DOCA-sal, têm aumento da concentração plasmática de OUA. Interagindo com a Na+/K+ ATPase, a OUA ativa vias de proliferação e fibrose, como a via MAPK, ativada quando da fosforilação da c-Src e do EGFR. A rostafuroxina, antagonista da OUA, reduz a pressão arterial (PA) e melhora a disfunção endotelial em AMR de ratos DOCA-sal. Dados do laboratório (não publicados) mostram que a rostafuroxina reverte o remodelamento mecânico e restaura parcialmente o remodelamento estrutural das AMR de ratos DOCA-sal. Assim, o objetivo deste trabalho foi avaliar os mecanismos de sinalização celular envolvidos nas mudanças estruturais e mecânicas das AMR de ratos DOCA-sal tratados com rostafuroxina. Ratos Wistar, uninefrectomizados, foram tratados com injeções subcutâneas de DOCA (em mg/kg/semana: 20 na primeira; 12 na segunda e terceira; 6 da quarta ao fim do experimento) e ingeriram água com NaCl (1%) e KCl (0,2%). Cinco semanas após o início do tratamento, um subgrupo passou a ser tratado, concomitantemente, com rostafuroxina (gavagem, 1mg/kg/dia) por 3 semanas. Ao final do protocolo, os animais foram anestesiados, mortos, as AMR dissecadas e fixadas em paraformaldeído (4%) para as análises histológicas ou armazenadas para Western Blot. Análise estatística aplicada: ANOVA uma ou duas vias. Avaliada por meio da plestismografia de cauda, o tratamento com DOCA-sal aumentou a PA; a rostafuroxina reduziu, mas não normalizou a mesma aos valores do grupo SHAM. A razão de colágeno I/III e a expressão proteica dos mediadores fibróticos TGFβ1 e CTGF foi maior nas AMR dos DOCA, alterações restauradas após tratamento com rostafuroxina. Além do mais, houve aumento da espessura da lâmina elástica interna das AMR dos DOCA, o que foi revertido pela rostafuroxina. A expressão de endotelina-1 foi maior nas AMR tanto dos DOCA tratados ou não com rostafuroxina; a expressão do receptor ETΑ foi reduzida nas AMR de ambos os grupos. Já a expressão do receptor ETΒ foi maior nas AMR dos DOCA quando comparados aos SHAM, sendo normalizada pela rostafuroxina. A expressão de c-SrcTyr418 e EGFR, bem como das enzimas c-RAF, ERK 1/2, p-ERK 1/2 e p38MAPK foi maior nas AMR dos DOCA, sendo restauradas com a rostafuroxina. Os dados sugerem que o remodelamento das AMR do grupo DOCA pode ser atribuído à ação direta da OUA sobre a via fibrótica e sobre a elastina, interferindo na rigidez e no diâmetro interno, e também à sua ação indireta, mediada pela endotelina-1 que, agindo em receptores ETB e transativando o EGFR, ativa a via da MAPK, a qual está associada aos eventos de proliferação e fibrose celular. / Na+/K+ ATPase inhibitors, such as ouabain (OUA), are associated with genesis/maintenance of hypertension. Rats treated with OUA are hypertensive and their mesenteric resistance arteries (MRA) exhibit vascular dysfunction, oxidative stress and structural and mechanical remodeling. Volume-dependent hypertensive models, as DOCA-salt, have increased plasmatic OUA levels. Interacting with Na+/K+ ATPase, OUA activates proliferation and fibrosis pathways, such as MAPK pathway, which is activated from c-Src and EGFR phosphorylation. Rostafuroxin, an OUA antagonist, reduces arterial pressure (AP) and improves endothelial dysfunction in MRA of DOCA-salt rats. Unpublished data of our laboratory have shown that rostafuroxin reverses the mechanical and partially restores the structural remodeling of MRA of DOCA-salt rats. Thus, the aim of this study was to evaluate the cellular signaling mechanisms involved in the structural and mechanical changes in MRA of DOCA-salt rats treated with rostafuroxin. Male Wistar rats, uninephrectomized, were treated with subcutaneous injections of DOCA (mg/kg/week: 20 in the 1st; 12 in the 2nd and 3rd; 6 from 4th to the end of the experiment) and drunk water with NaCl (1%) and KCl (0,2%). After 5 weeks of treatment, a subgroup started being treated, concomitantly, with rostafuroxin (gavage, 1mg/kg/day) for 3 weeks. At the end of the protocol, animals were anesthetized, killed, the MRA dissected out and fixed in paraformaldehyde (4%) to histological analyses or stored to Western Blot. Statistical analysis applied: ANOVA one- or two-way. Evaluated by pletismography, the DOCA-salt treatment raised the AP levels; rostafuroxin reduced it, but did not normalized to the values of SHAM group. Collagen I/III ratio and protein expression of fibrosis mediators TGFβ1 and CTGF was higher in MRA of DOCA and rostafuroxin restored these parameters. In addition, an increment in the thickness of inner elastic lamina was observed in MRA of DOCA, which was reversed by rostafuroxin treatment. Endothelin-1 expression was higher in MRA of both DOCA and rostafuroxin treated rats; ETΑ receptor was less expressed in both groups. On the other hand, ETΒ was more expressed in MRA from DOCA and normalized to SHAM levels by rostafuroxin treatment. The expression of c-SrcTyr418 and EGFR, as well as of the enzymes c-RAF, ERK 1/2, p-ERK 1/2 and p38MAPK was higher in MRA of DOCA when compared to SHAM, being restores with rostafuroxin. Taken together, the present data suggest that MRA remodeling in DOCA group can be attributed to direct action of OUA on elastin and fibrotic pathway, interfering in stiffness and inner diameter, as well as to its indirect action, mediated by endothelin-1, which acting in ETB receptors and activating EGFR, activates MAPK pathway, which is associated to proliferation and fibroses events.

A ouabaína (OUA), um inibidor da Na+ ,K+-ATPase, foi identificada como uma substância endógena presente no plasma humano, e parece estar envolvida na resposta ao estresse agudo, em animais e seres humanos. O estresse crônico é um importante fator agravante de doenças psiquiátricas, incluindo depressão e ansiedade. Além disso, problemas cognitivos são cada vez mais reconhecidos como importantes componentes da ansiedade e depressão. Diante disto, o presente trabalho buscou investigar os efeitos da OUA (1,8 <font face = \"symbol\">mg/kg) na hiperatividade do eixo HPA, na neuroinflamação, na expressão de receptores e proteínas envolvidos na plasticidade sináptica, nos efeitos comportamentais (como déficit de memória de longa duração, depressão e ansiedade) e atividade da Na+,K+-ATPase induzidos pelo protocolo de estresse crônico imprevisível (CUS) realizado ao longo de 14 dias em ratos. Nossos resultados demonstraram que o tratamento intermitente com OUA é capaz de reverter a hiperatividade do eixo HPA induzido pelo CUS, por meio da redução de glicocorticoide, redução na expressão de CRH-CRHR1, bem como diminuir a neuroinflamação, e aumentar os níveis de BDNF e fazer o que na expressão dos receptores CRHR2. Essas alterações bioquímicas contribuíram para uma reversão nos prejuízos na memória de longo prazo induzida pelo CUS. Ademais os animais tratados apenas com OUA, bem como os submetidos ao CUS e tratados com OUA obtiveram uma melhora na memória emocional, averiguada no teste comportamental de condicionamento da memória ao medo. Os resultados encontrados sugerem que o protocolo de CUS por 14 dias promove uma adaptação neuronal facilitando a redesignação da memória ao medo, aqui configurado pelo choque, e o tratamento com a OUA abrevia esse processo. Em conclusão os nossos resultados sugerem que o tratamento intermitente com OUA suscita uma adaptação no eixo HPA, por meio de alterações na expressão dos receptores para CRH no hipocampo e hipotálamo, resultando em uma adaptação na memória emocional relacionada ao medo. / Ouabain (OUA), an inhibitor of Na+, K+ -ATPase, has been identified as an endogenous substance present in human plasma, and appears to be involved in the response to acute stress in animals and humans. Chronic stress is an important aggravating factor of psychiatric illness, including depression and anxiety. In addition, cognitive problems are increasingly recognized as important components of anxiety and depression. The present work aimed to investigate the effects of OUA (1.8 <font face = \"symbol\">mg/kg) on HPA axis hyperactivity, neuroinflammation, expression of receptors and proteins involved in synaptic plasticity, behavioral effects (such as long-term memory deficit duration, depression and anxiety) and Na+,K+-ATPase activity induced by the unpredictable chronic stress protocol (CUS) performed over 14 days in rats. Our results demonstrated that intermittent treatment with OUA was able of reversing CUS-induced HPA axis hyperactivity, by reducing glucocorticoid levels, CRH-CRHR1 expression, as well as reducing CUS-induced low-grade neuroinflammation, and increase BDNF levels and expression of CRHR2 receptors. These biochemical changes contributed to a reversal in CUS-induced long-term memory impairment. In addition, animals treated only with OUA, as well as those submitted to CUS, and also treated with OUA obtained an improvement in emotional memory, which was explored in the fear conditioning test. These results suggest that the CUS protocol of 14 days promotes a neural adaptation facilitating a reassignment of the memory to the fear, here configured by the shock, and the treatment with the OUA shortens that process. In conclusion, our results suggest that intermittent treatment with OUA induces an adaptation on the HPA axis, through alterations in the expression of receptors for CRH in the hippocampus and hypothalamus, resulting in an adjustment in fear-related emotional memory.