Water deprivation and the double- depletion hypothesis: common neural mechanisms underlie thirst and salt appetite

Water deprivation-induced thirst is explained by the double-depletion hypothesis, which predicts that dehydration of the two major body fluid compartments, the extracellular and intracellular compartments, activates signals that combine centrally to induce water intake. However, sodium appetite is also elicited by water deprivation. In this brief review, we stress the importance of the water-depletion and partial extracellular fluid-repletion protocol which permits the distinction between sodium appetite and thirst. Consistent enhancement or a de novo production of sodium intake induced by deactivation of inhibitory nuclei (e.g., lateral parabrachial nucleus) or hormones (oxytocin, atrial natriuretic peptide), in water-deprived, extracellular-dehydrated or, contrary to tradition, intracellular-dehydrated rats, suggests that sodium appetite and thirst share more mechanisms than previously thought. Water deprivation has physiological and health effects in humans that might be related to the salt craving shown by our species.

A2 Noradrenergic Lesions Prevent Renal Sympathoinhibition Induced by Hypernatremia in Rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The in vivo electrical parameters of toad skin

1. 1. Open-circuit voltage (PD) and short-circuit current (SCC) across toad skin were studied in in vivo conditions. An improved technique for fastening a lucite chamber on the abdominal region of the animal was developed. 2. 2. Saline bridges (230 mM Nacl in 4% agar solution) were placed subcutaneously to make the connections between the extracellular fluid and the half-cells. 3. 3. A clear relationship was observed between the electrical parameters and sodium transport by the skin, since PD and SCC were related to the sodium concentration of the bathing solution, and abolished by the presence of amiloride-a specific sodium transport inhibitor in epithelia. 4. 4. The initial control values of SCC in vivo were higher than those in vitro, which was attributed to hormonal stimulation. However, these high initial control values of SCC in vivo fell with time, reaching steady levels after a 2 hr period. 5. 5. Vasopressin failed to increase SCC in vivo when the external sodium concentration was 115 mM, being effective only when the sodium concentration was low (5 mM). 6. 6. On the other hand, in isolated preparations vasopressin significantly promoted an increase in both PD and SCC. © 1983.

Purificação de lacases PPO-I de Botryosphaeria rhodina

Laccases are glycoprotein polyphenol oxidases which are involved in fungal pathogenicity and they are also useful for biotechnological applications. The ligninolytic ascomycete, Botryosphaeria rhodina, has been studied as producer of exopolysaccharide and PPO-I and PPO-II laccases induced by veratryl alcohol. However, as the induced laccases have not been isolated, the aim of this study was to purify the enzyme and to identify the carbohydrates constituents of the glycosidic moiety. The fungus was cultivated on broth Vogel, 1% glucose and 30.4mM veratryl alcohol during 4.5 days at 28°C/180 rpm. The extracellular fluid showed high carbohydrate concentration and the stability of PPO-I laccase under conditions of refrigeration and freezing at 4°C-18°C over 40 days. The purification was developed by ultrafiltration using a NMWL 100 and 30 kDa membrane, gelfiltration on Sephadex G-100, and ion-exchange chromatography on DEAE-cellulose. The purified laccase was identified as a glycoprotein, weight molecular 113 kDa, consisting of 40% protein and 60% carbohydrate identified by HPAEC-PAD as fucose, galactose, mannose, glucose and glucosamine.

Could albumin level explain the higher mortality in hemodialysis patients with pulmonary hypertension?

Background: The pathogenesis of pulmonary hypertension (PH) in hemodialysis is still unclear. The aim of thisstudy was to identify the risk factors associated with the presence of PH in chronic hemodialysis patients and toverify whether these factors might explain the highest mortality among them.Methods: We conducted a retrospective study of hemodialysis patients who started treatment from August 2001to October 2007 and were followed up until April 2011 in a Brazilian referral medical school. According to theresults of echocardiography examination, patients were allocated in two groups: those with PH and those withoutPH. Clinical parameters, site and type of vascular access, bioimpedance, and laboratorial findings were comparedbetween the groups and a logistic regression model was elaborated. Actuarial survival curves were constructed andhazard risk to death was evaluated by Cox regression analysis.Results: PH > 35 mmHg was found in 23 (30.6%) of the 75 patients studied. The groups differed in extracellularwater, ventricular thickness, left atrium diameter, and ventricular filling. In a univariate analysis, extracellular waterwas associated with PH (relative risk = 1.194; 95% CI of 1.006 1.416; p = 0.042); nevertheless, in a multiple model,only left atrium enlargement was independently associated with PH (relative risk =1.172; 95% CI of 1.010 1.359;p = 0.036). PH (hazard risk = 3.008; 95% CI of 1.285 7.043; p = 0.011) and age (hazard risk of 1.034 per year of age;95% CI of 1.000 7.068; p = 0.047) were significantly associated with mortality in a multiple Cox regression analysis.However, when albumin was taken in account the only statistically significant association was between albuminlevel and mortality (hazard risk = 0.342 per g/dL; 95% CI of 0.119 0.984; p = 0.047) while the presence of PH lost itsstatistical significance (p = 0.184). Mortality was higher in patients with PH (47.8% vs 25%) who also had astatistically worse survival after the sixth year of follow up.Conclusions: PH in hemodialysis patients is associated with parameters of volume overload that sheds light on itspathophysiology. Mortality is higher in hemodialysis patients with PH and the low albumin level can explain thisassociation.© 2012 Greenfield et al.; licensee BioMed Central Ltd.

Effect of dialysate sodium reduction on body water volume, blood pressure, and inflammatory markers in hemodialysis patients - A prospective randomized controlled study

Accumulating evidence suggests an association between body volume overload and inflammation in chronic kidney diseases. The purpose of this study was to evaluate the effect of dialysate sodium concentration reduction on extracellular water volume, blood pressure (BP), and inflammatory state in hemodialysis (HD) patients. In this prospective controlled study, adult patients on HD for at least 90 days and those with C-reactive protein (CRP) levels ≥ 0.7 mg/dL were randomly allocated into two groups: group A, which included 29 patients treated with reduction of dialysate sodium concentration from 138 to 135 mEq/L; and group B, which included 23 HD patients not receiving dialysate sodium reduction (controls). Of these, 20 patients in group A and 18 in group B completed the protocol study. Inflammatory, biochemical, hematological, and nutritional markers were assessed at baseline and after 8 and 16 weeks. Baseline characteristics were not significantly different between the two groups. Group A showed a significant reduction in serum concentrations of tumor necrosis factor-α, and interleukin-6 over the study period, while the BP and extracellular water (ECW) did not change. In Group B, there were no changes in serum concentrations of inflammatory markers, BP, and ECW. Dialysate sodium reduction is associated with attenuation of the inflammatory state, without changes in the BP and ECW, suggesting inhibition of a salt-induced inflammatory response. Copyright © 2013 Informa Healthcare USA, Inc.

Efeitos numéricos na simulação de escoamentos gás-sólido em leito fuidizado borbulhante utilizando a teoria cinética dos escoamentos granulares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo hidrogeoquímico da porção meridional do sistema aquífero Bauru no estado de São Paulo

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

Efeitos da expansão de volume extracelular sobre o conteúdo de catecolaminas e a ativação neuronal de estruturas do hipotálamo e do tronco cerebral de ratos

A regulação fina do volume e osmolaridade dos líquidos corporais é fundamental para a sobrevivência. Qualquer variação na composição do meio interno ativa mecanismos comportamentais, neurais e hormonais compensatórios que controlam a ingestão e excreção de água e eletrólitos a fim de manter a homeostase hidroeletrolítica. Alterações na faixa de 1-2% na osmolaridade sanguínea estimulam a liberação de arginina vasopressina (AVP) que resulta em antidiurese além de ocitocina (OT) e peptídeo natriurético atrial (ANP) que promovem a natriurese. Trabalhos realizados em nosso laboratório utilizando o modelo experimental de expansão do volume extracelular (EVEC) mostraram ativação de neurônios magnocelulares ocitocinérgicos localizados no núcleo paraventricular (PVN) e núcleo supra-óptico (SON) responsáveis pela secreção de OT e AVP, igualmente alteradas em resposta a este estímulo. A participação do sistema nervoso simpático nestas condições tem sido levantada. Projeções medulares e tronco-encefálicas (simpáticas) para o hipotálamo poderiam atuar de forma seletiva inibindo sinalizações para a ingestão e estimulando sinalizações para excreção de água e eletrólitos. O papel de vias noradrenérgicas tronco-encefálicas nesta regulação ainda precisa ser mais bem estabelecido. Assim sendo, objetivamos neste estudo esclarecer o papel do sistema nervoso simpático (via noradrenérgicas) na regulação das alterações induzidas pelo modelo de EVEC, analisando por cromatografia líquida de alta eficácia o conteúdo de noradrenalina (NA), adrenalina (AD) e serotonina (5-HT) em estruturas do tronco cerebral como núcleo do trato solitário (NTS), bulbo rostro-ventro lateral (RVLM), locus coeruleus (LC) e núcleo dorsal da rafe (NDR) e estruturas hipotalâmicas como SON e PVN. Procuramos ainda, através de estudos imunocitoquímicos determinar alterações no padrão de ativação neuronal pela análise de Fos-TH ou Fos-5HT nas estruturas acima mencionadas em condições experimentais nas quais são induzidas alterações do volume do líquido extracelular.

Anticorpos policlonais e monensina sódica na alimentação de bovinos jovens confinados com dietas de alto concentrado

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

Modulação dos sistemas GABAérgico e glutamatérgico na secreção hipotalâmica de ocitocina sob condições hiperosmóticas

Em mamíferos, a osmolalidade do fluído extracelular é o parâmetro mais importante na manutenção do balanco hidroeletrolitica. Deste modo, variações de osmolalidade são detectadas por células hipotalâmicas especializadas, iniciando assim uma sinalização neuroquímica, com envolvimento dos sistemas glutamátergicos e GABAérgico, a qual pode desencadear a secreção da ocitocina. Entretanto, o modo como a relação dos aminoácidos GABA e glutamato pode modular a liberação de ocitocina durante a hiperosmolalidade ainda é pouco compreendida. Neste contexto, o objetivo do presente estudo foi caracterizar o efeito do meio hipertônico sobre os níveis extracelulares de GABA e glutamato e sua relação com a liberação de ocitocina em preparações de hipotálamo in vitro. Para tal, Ratos Wistar Machos (270-300g) foram mantidos em condições padrões de laboratório. E após decapitação o cérebro foi retirado rapidamente, os fragmentos hipotalâmicos foram imediatamente dissecados em Krebs Ringer Bicarbonato Glicose gelado (KRBG) e colocados no sistema de perinfusão com solução de KRBG isotônica (280 mOsm/Kg H₂O) fluxo de 0.5-1.0 ml/min, foram feitas as coletas a cada minuto durante 15 min. O estímulo hipertônico (340 mOsm/Kg H₂O) ocorreu por 3 minutos. As dosagens de glutamato, GABA e ocitocina foram efetuadas por Cromatografia Líquida de Alta Eficiência (HPLC). As dosagens de glutamato mostraram um aumento da liberação somente após a diminuição da concentração de GABA. Este padrão de liberação temporal motivou-nos a adicionar GABA (3 μM) durante o estímulo osmótico, resultando no bloqueio da liberação de glutamato anteriormente observada. Além disso, os resultados mostraram que a liberação de ocitocina estimulada por solução de NaCl hipertônica pode depender também de uma diminuição da liberação de GABA. O presente estudo sugere que a liberação de ocitocina estimulada por hipertonicidade depende de alteração da relação GABA/glutamato.

Caracterização hidroquímica do sistema aquífero Tubarão no município de Americana/SP

The growing interest in the use of groundwater resources is directly related to the economic advantages that the groundwater exploitation offers when compared to surface waters. This happens especially in large urban centers, such as the city of Americana / SP, where the rivers are increasingly contaminated by household and industrial waste. Therefore, this study aimed to characterize the Tubarão Aquifer System, in the city of Americana, to identify and evaluate the spatial distribution of different hydrogeochemical facies as well as understand the rock-fluid interaction through the construction of a conceptual hydrogeochemical model. This study was made based on the recognition of the possible chemical reactions that print the chemical characteristics of groundwater in the area. To do the job, there were two water sampling campaigns of all deep wells used by the City of Americana public water supply. From the results of hydrochemical, classification of water was made by Piper and Stiff diagrams as well as geostatistical data using cluster analysis of principal components. Based on information from the profiles obtained from the survey SIAGAS as well as in geological profiles provided by the city of Americana, we sought to detail the subsurface geology of the Subgroup Itararé in the city of Americana. The results obtained allowed the identification of three hydrochemical types in the study area: Bicarbonated calcium-sodium (1), bicarbonate sodium (2) and sodium chloride (3). The waters have bicarbonate alkaline pH to alkaline and can be considered weakly saline, with electrical conductivity values of around 161 mS / cm. Samples classified as sodium bicarbonate average of 174.99 mS / cm. The pH values ranging from 6.74 to 7.99, averaging 7.52. For the group of waters classified as sodium chloride, conductivity average is 164.32 mS / cm and pH values ranging... (Complete abstract click electronic access below)

Caracterização hidrogeoquímica, isotópica e diagenética do sistema aquífero Bauru no Estado de São Paulo

Pós-graduação em Geociências e Meio Ambiente - IGCE

Caracterização hidrogeoquímica, isotópica e diagenética do sistema aquífero Bauru no Estado de São Paulo

Pós-graduação em Geociências e Meio Ambiente - IGCE

Increased NHE3 abundance and transport activity in renal proximal tubule of rats with heart failure

Inoue BH, dos Santos L, Pessoa TD, Antonio EL, Pacheco BPM, Savignano FA, Carraro-Lacroix LR, Tucci PJF, Malnic G, Girardi ACC. Increased NHE3 abundance and transport activity in renal proximal tubule of rats with heart failure. Am J Physiol Regul Integr Comp Physiol 302: R166-R174, 2012. First published October 26, 2011; doi:10.1152/ajpregu.00127.2011.-Heart failure (HF) is associated with a reduced effective circulating volume that drives sodium and water retention and extracellular volume expansion. We therefore hypothesized that Na(+)/H(+) exchanger isoform 3 (NHE3), the major apical transcellular pathway for sodium reabsorption in the proximal tubule, is upregulated in an experimental model of HF. HF was induced in male rats by left ventricle radiofrequency ablation. Sham-operated rats (sham) were used as controls. At 6 wk after surgery, HF rats exhibited cardiac dysfunction with a dramatic increase in left ventricular end-diastolic pressure. By means of stationary in vivo microperfusion and pH-dependent sodium uptake, we demonstrated that NHE3 transport activity was significantly higher in the proximal tubule of HF compared with sham rats. Increased NHE3 activity was paralleled by increased renal cortical NHE3 expression at both protein and mRNA levels. In addition, the baseline PKA-dependent NHE3 phosphorylation at serine 552 was reduced in renal cortical membranes of rats with HF. Collectively, these results suggest that NHE3 is upregulated in the proximal tubule of HF rats by transcriptional, translational, and posttranslational mechanisms. Enhanced NHE3-mediated sodium reabsorption in the proximal tubule may contribute to extracellular volume expansion and edema, the hallmark feature of HF. Moreover, our study emphasizes the importance of undertaking a cardiorenal approach to contain progression of cardiac disease.