Orientador: Ciro Antonio Rosolem / Banca: Alberto Carlos de Campos Bernardi / Banca: Paulo Sérgio Pavinato / Banca: José Salvador Simoneti Foloni / Banca: Juliano Carlos Calonego / Resumo: Estudos que contemplem o balanço de potássio (K) no sistema solo-planta são importantes para avaliar se as quantidades de fertilizantes aplicadas anualmente estão sendo aproveitadas para manter e/ou, melhorar a fertilidade do solo, ou estão intensificando as perdas de K por lixiviação. O objetivo deste estudo foi avaliar o efeito da adubação potássica no balanço de K no sistema solo-planta em dois solos tropicais de texturas distintas. Os experimentos foram conduzidos na Fazenda Experimental Lageado, em Botucatu, SP, de 2000 a 2012, em um Latossolo Vermelho de textura média (210 g kg-1 de argila) e em outro Latossolo Vermelho de textura argilosa (680 g kg-1 de argila). Os tratamentos foram constituídos por sete doses de K aplicadas anualmente (0, 30, 60, 90, 120, 150 e 180 kg ha-1 ano-1 de K2O). O balanço de K no sistema solo-planta foi estimado, após o décimo segundo ano de experimento, considerando a quantidade do nutriente adicionada na adubação, a quantidade de K exportada da lavoura através dos grãos colhidos, e a alteração na disponibilidade de K trocável no perfil do solo, até 1,0 m de profundidade. Amostras de solo foram coletadas nas camadas de 0-0,10; 0,10-0,20; 0,20-0,40; 0,40-0,60; 0,60-0,80 e 0,80-1,0 m de profundidade no 12º ano de condução do experimento. O teor inicial de 1,30 e 0,75 mmolc dm-3 de K trocável na camada de 0-0,20 m de profundidade nos solos de textura média e argilosa, respectivamente, foi suficiente para atingir produtividade de grãos de soja superior a 90 % do rendimento máximo nos três e quatro primeiros anos de cultivo, respectivamente, não havendo necessidade de adubar com K, devido à contribuição do K não-trocável. A resposta da cultura à adubação potássica aumentou à medida que os cultivos se sucederam, e esse aumento correspondeu à diminuição das reservas disponíveis do nutriente no solo ... / Abstract: Studies that include potassium budget (K) in the soil-plant system are important to assess whether the amounts of fertilizer applied annually are being harnessed to maintain and or improve soil fertility, or are intensifying K losses by leaching. The objective of this study was to evaluate the effect of potassium fertilization on the K budget in soil-plant system in two tropical soils with different textures. The experiments were carried out at the Experimental Farm Lageado in Botucatu, SP, 2000-2012, on a medium texture Oxisol (210 g kg-1 clay ) and other clay Oxisol (680 g kg-1 clay). Treatments consisted of seven levels of K applied annually (0, 30, 60, 90, 120, 150 and 180 kg ha-1 yr-1 K2O). Soil samples were collected at depths of 0-0.10; 0.10-0.20; 0.20-0.40; 0.40-0.60; 0.60-0.80 and 0.80-1.00 m in the twelfth year of the experiment. Potassium budget in the soil-plant system was calculated based on (i) amount of nutrient inputs (fertilizer) and outputs (harvested grains) from the soil during the experiment, and on (ii) changes in soil K availability up to a depth of 1.0 m. The initial content of 1.30 and 0.75 mmol dm-3 of exchangeable K in the soil medium and clay texture was enough to achieve higher productivity soybeans at 90% of maximum yield in the first three to four years of cultivation, respectively, no need to fertilize with K because the contribution of non-exchangeable K. The crop response to potassium fertilization increased, as the succeeding crops, and this increase corresponded to a decrease in soil nutrient reserves available. The annual application of 80 and 40 kg ha-1 K2O was sufficient to meet crop demand and maintain a constant level of exchangeable K in the soil of clayey and silty , respectively texture. Increasing the dose of potassium fertilizer intensified K losses by leaching the soil of medium texture, which ranged 4-78 kg ha-1 ... / Doutor

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Circadian rhythms refer to the physiological and biological processes that fluctuate over a 24-hour period. These rhythms are found in most living things such as animals, plants and fungi. In mammals, circadian rhythms are mainly generated and regulated by the suprachiasmatic nucleus (SCN).The period (Per1) gene in the SCN plays a key role in directing circadian rhythms. Per1 expression increases during the day and decreases at night. The neurons which express the Per1 gene show different behaviours to non-Per1 neurons during the day-night cycle. Per1 neurons are in a state of repetitive firing in the morning while in the late morning they display a bursting behaviour. In the afternoon, Per1 neurons divide into two groups: GA and GB, where GA is in a repetitive firing state and GB is silent. At night, these neurons are generally in a quiescent state but late at night they generate spikes. In this study, a standard Hodgkin-Huxley type model was used to study the behaviours of Per1 neurons over the day-night cycle using bifurcation analysis. In this model, the potassium and calcium currents carry the circadian rhythms which are modelled by their conductance. The currents had a significant impact on Per1 neuron behaviours. Furthermore, by changing some of the model parameters, different bistability mechanisms were examined. The study was extended to explore the effect of noise from other neurons on Per1 neuron behaviours. It was shown that noise plays a crucial role in inducing some of the Per1 neuron behaviours and that some Per1 neuron behaviours are fully induced by this noise, e.g. the late morning and late night behaviours. In contrast, the noise was found not to have any significant effect on other Per1 neuron behaviours other than the two behaviours that are observed in the afternoon.

A combustão do carvão para a produção de energia elétrica tem como consequência a geração de cinzas, que é um dos maiores resíduos gerados no Brasil, em termos de volume (4.109 dm³/ano). Visando a minimização do impacto ambiental causado pelo mau descarte das cinzas, este trabalho teve como objetivo sintetizar e caracterizar zeólitas obtidas a partir de cinza de carvão e aplicar na agricultura como fertilizante potássico. Para isso a cinza utilizada foi obtida no combustor piloto de leito fluidizado operando com carvão da Mina do Leão/RS e empregada para sintetizar material zeolítico a partir do tratamento hidrotérmico alcalino. Foram realizados ensaios experimentais utilizando razão solução/cinzas constante em 6 L mg-1, variando a concentração de hidróxido de potássio (KOH) entre 3 e 5 M, a temperatura entre 100 e 150 ºC e o tempo de reação entre 24 e 72 h. O material sintetizado e a cinza foram caracterizados quanto a sua composição química, mineralógica, morfologia, área superficial específica e capacidade de troca catiônica. Através da caracterização foi observada a formação de duas fases zeolíticas, a chabazita-K e a merlinoíta. A partir da caracterização do material, foi escolhido um dos produtos zeolíticos obtidos para aplicação em solo, como fertilizante de potássio para o cultivo de trigo (Triticum aestivum L.). A condição experimental escolhida foi de 5 M a concentração da solução de KOH, temperatura de 150 ºC e tempo de reação de 24 h. Nesta condição obteve-se apenas uma fase zeolítica identificada, a zeólita merlinoíta, com uma área superficial de 23,37 m² g e uma capacidade de troca catiônica (CTC) de 2,62 meq g 1. Para fins de comparação foi utilizado o fertilizante comercial, cloreto de potássio (KCl), que contém em torno de 60 % de K2O. Foram realizados 35 ensaios experimentais em casa de vegetação da EMBRAPA, utilizando 7 tratamentos (3 doses diferentes de KCl e zeólita 50, 100 e 150 % da dose máxima recomendada e o solo não tratado (testemunha)) em 5 blocos aleatórios. Os experimentos na casa de vegetação foram concluídos com 59 dias de cultivo de trigo e submetidos às análises como determinação da produção de matéria seca da parte aérea e raízes das plantas e análise química do solo e tecido foliar. Verificou-se que a zeólita merlinoíta obtida a partir da cinza de carvão pode ser utilizada como fertilizante, pois teve um desempenho similar ao KCl no crescimento do trigo, não inibindo seu crescimento. Utilizando o tratamento com zeólita 100 % a produção de matéria seca da parte aérea foi de 1,07 ± 0,09 g e raízes 1,6 ± 0,23 g e na análise do tecido foliar teve uma absorção de 3,39 ± 0,31. / Coal combustion for electricity production results in the generation of ash, which is one of the main waste generated in Brazil in terms of volume. Intending the minimization of the environmental impact caused by poor disposal of ashes, this study aimed to synthesize and characterize zeolites obtained from coal ash and apply in agriculture as potassium fertilizer. For this purpose, coal fly ash was obtained from a fluidized bed pilot combustor operating with coal from Mina do Leão/RS and used to synthesize zeolitic material through the alkaline hydrothermal treatment. Experimental tests were performed using the ratio volume of solution/mass of coal fly ash constant at 6 mL mg -1, varying the concentration of potassium hydroxide (KOH) between 3 and 5 M, temperature between 100 and 150 °C and reaction time between 24 and 72 h. The synthesized and coal fly ash material was characterized by their chemical composition, mineralogy, morphology, specific surface area and cation exchange capacity. With the characterization, it was observed the formation of two phases zeolite K-chabazite and merlinoite. By the characterization of the material, it was chosen one of the zeolitic products obtained for application to soil as a potassium fertilizer for the cultivation of wheat (Triticum aestivum L.). The chosen experimental condition was 5 M KOH solution, temperature of 150 °C and 24 h time of reaction. At this condition, only one zeolitic phase was identified, zeolite merlinoite, with a surface area of 23.37 m² g a cation exchange capacity (CEC) of 2.62 meq g-1. For purposes of comparison, the tests in the soil were performed using also a commercial fertilizer, potassium chloride (KCl), containing about 60 % of K2O. A total of 35 experimental trials were carried out in a greenhouse at EMBRAPA, using 7 treatments in 5 random blocks: 50, 100 and 150 % of the maximum recommended dose for KCl and for zeolite and untreated soil (witness). The experiments in the greenhouse were concluded with 59 days of wheat cultivation. The plants were submitted to analysis for dry matter in aerial parts and roots determination. Likewise, soil and foliar tissue were submitted to chemical analysis. It was found that the zeolite Merlinoite obtained from the coal fly ash can be used as a fertilizer because it had a similar performance to KCl in the wheat growth. The treatment with 100% zeolite presented a dry matter production of 1.07 ± 0.09 g for aerial parts and 1.6 ± 0.23 g for roots. Also, the leaf tissue analysis showed a potassium absorption of 3.39 ± 0.31 % m/m in this treatment.

A debilitating illness, pulmonary arterial hypertension (PAH) arises from deleterious remodeling of pulmonary arterioles, leading to increased pulmonary artery pressure, a rise in pulmonary vascular resistance, right sided heart failure and death. The pathogenesis of the disease is incompletely understood; however, certain established pathological features have guided medical treatments to improve mortality rates. For instance, an imbalance of vasoconstrictor molecules, such as endothelin-1, to vasodilator compounds, such as nitric oxide, contributes to excessive pulmonary arterial constriction, and a propensity for pulmonary arterial smooth muscle and endothelial cell proliferation. Therapeutic strategies may aim to restore this imbalance with the use of endothelin receptor antagonists, prostacyclin analogs, and other vasodilating agents. Mutations in the BMPR2 gene, the most common genetic cause of PAH, leads to aberrant TGF-ß signaling, which promotes uncontrollable cell proliferation and pathological changes in pulmonary arterioles. Genetic studies have revealed PAH-associated mutations in several other genes within the TGF-ß signaling pathway. More recently, our research group discovered loss-of-function mutations in the KCNK3 gene encoding the KCNK3 two-pore domain potassium channel in patients with idiopathic and familial PAH. KCNK3 (also referred to as TASK-1, or K2P3.1) represents the first ion channelopathy as a cause of PAH. KCNK3 is expressed in human pulmonary artery smooth muscle and endothelial cells. Loss of KCNK3 channel currents leads to membrane depolarization and predisposes to deleterious pulmonary arterial remodeling. Chapter 1 of my thesis explores the impact of KCNK3 mutations on potassium channel function in cellular models of heterozygous conditions, as all patients with PAH-associated KCNK3 mutations in our study were heterozygous at the KCNK3 gene locus. Furthermore, we explored function of mutant and non-mutant KCNK3 channels in cultured human pulmonary artery smooth muscle cells to better define the electrophysiological consequence of KCNK3 dysfunction, and used a KCNK3-activating pharmacological agent, ONO-RS-082, to gauge the therapeutic potential of KCNK3 as a pharmacological target in PAH. Moreover, the study of KCNK3 channel activity when assembled with the closely related KCNK9 channel provided a platform for exploring the lung-specific phenotype in patients with heterozygous KCNK3 mutations, despite widespread tissue expression KCNK3 in the body. In Chapter 2 of my thesis work, the discovery of a second potassium channelopathy in PAH is characterized. Heterozygous mutations in the ABCC8 gene, encoding the sulfonylurea receptor 1 (SUR1) protein, were found in pediatric and adult patients with idiopathic and familial PAH. SUR1, a beta subunit of the ATP-sensitive potassium channel (KATP), assembles with the pore-forming Kir6.2 alpha subunit to form KATP, a channel sensitive to inhibition by intracellular ATP. At the plasma membrane, KATP inwardly rectifying potassium currents contribute to the resting potential, and may play a pathophysiological role in PAH via dysfunction in pulmonary artery smooth muscle and/or endothelial cells. In this chapter, eight ABCC8 mutations associated with PAH were functionally characterized, and pharmacological agents were employed to examine the therapeutic potential in targeting SUR1-containing KATP channels in PAH. Altogether, the research presented in this dissertation identifies and explores potassium channel dysfunction as a pathogenic mechanism in PAH, due to heterozygous genetic mutations in KCNK3 and ABCC8. Evidence of restoration of mutant KCNK3 and KATP channel function by pharmacological agents suggests that targeting potassium channels as a therapeutic strategy may alleviate the severe morbidity and mortality burden in patients with PAH.

Orientador: Roberto Lyra Villas Bôas / Banca: Dirceu Maximino Fernandes / Banca: Rumy Goto / Banca: Caroline de Moura D'Andrea Mateus / Banca: Luiz Vitor Crepaldi Sanches / Resumo: O excesso da adubação pode causar prejuízos na cultura do pimenteiro e danos ao meio ambiente. Por isso, a escolha do fertilizante e a aplicação de uma solução nutritiva equilibrada são fundamentais para a produção e qualidade do produto final. Assim, objetivou-se com o presente trabalho avaliar os efeitos do incremento da adubação potássica, utilizando diferentes fontes e doses potássicas na produção dos frutos de pimenteiro fertirrigado cultivado em substrato sob ambiente protegido, bem como monitorar o estado nutricional do pimenteiro por meio de métodos alternativos. As características avaliadas foram: CE e pH da solução do substrato, teores de nitrato e potássio na solução do substrato e na seiva das plantas, teores de macro e micronutrientes na massa seca foliar, índice SPAD, número de frutos total e comercial, produção total e comercial, massa fresca, comprimento e diâmetro dos frutos e as correlações entre essas variáveis. O experimento foi conduzido sob delineamento experimental de blocos ao acaso, em esquema fatorial 4 x 2 + 1, constituindo 9 tratamentos, com 4 repetições. Os tratamentos foram constituídos por duas fontes potássicas (KCl e K2SO4), 4 doses de potássio (125, 250, 375 e 500 mg L-1) e mais o controle (0 mg L-1). Observou-se que a dose de 300 mg L-1 de K, independente da fonte utilizada, proporcionou maior produção total e comercial do pimenteiro híbrido Platero. A CE no tratamento com KCl atingiu valor de 5,0 dS m-1, enquanto que com o K2SO4 o valor máximo foi de 3,5 dS m-1, ambos com ... / Abstract: Excess fertilizer can cause damage in sweet pepper cultivation and to the environment. Therefore, the choice of fertilizer and the application of a balanced nutrient solution are essential for the production and quality of the final product. Thus, the aim of the present study was to evaluate the effects of increasing potassium fertilizer, using different potassium sources and doses in the production of fertirrigated sweet pepper grown in substrate under greenhouse conditions as well as monitor the nutritional status of pepper through methods alternative. The characteristics evaluated were: EC and pH of the substrate solution, nitrate and potassium levels in the solution of the substrate and the sap of plants, macro and micronutrients in the leaf dry mass, SPAD index, number of total and marketable fruit, total production and commercial fresh mass, length and diameter of the fruits and the correlations between these variables. The experiment was conducted under 4 experimental design of randomized blocks in a factorial 4 x 2 + 1, constituting 9 treatments, with four repetitions. The treatments consisted of two sources potassic (KCl and K2SO4), four potassium doses (125, 250, 375 and 500 mg L-1) and more control (0 mg L-1). It was observed that the dose of 300 mg L-1 K, regardless of the source used, higher total production and commercial hybrid sweet pepper Platero. The EC of treatment with KCI has reached value of 5.0 dS m-1, while with K2SO4 the maximum value was 3.5 dS m-1, both the higher dose. The application of KCl increased number of fruits compared to K2SO4. Treatment with K2SO4 presented to both the 75 and 165 DAT, higher concentration of poatassium on the dry weight of leaves and of sulfur to DAT 165. A higher concentration of NO3- in the substrate solution occur with K2SO4 relative to KCl to 75 DAT, and to 165 DAT higher concentration of potassium in the substrate solution in the same ... / Doutor

nÃo hà / O cultivo do coqueiro anÃo vem crescendo no Cearà em virtude da grande procura do produto pelas grandes indÃstrias. Os objetivos do presente estudo foram avaliar: a) os efeitos de diferentes doses de nitrogÃnio e potÃssio, aplicadas via fertirrigaÃÃo, sobre o crescimento e produÃÃo do coqueiro anÃo cultivado em solos arenosos da regiÃo litorÃnea do CearÃ, b) determinar os nÃveis crÃticos desses nutrientes na folha da planta adulta e estabelecer as doses de N e K que propiciem a mÃxima eficiÃncia de resposta para a cultura nas condiÃÃes edafoclimÃticas da regiÃo do Estado do CearÃ. O trabalho foi conduzido em plantaÃÃo comercial de coqueiro anÃo implantada pela Embrapa AgroindÃstria Tropical em Ãrea de produtor (Latitude 3 17â Sul, Longitude 39 15â Oeste e altitude de 30 metros), no perÃodo de dezembro de 2002 a dezembro de 2003, no municÃpio de Paracuru-CE, prÃximo ao PerÃmetro Irrigado Curu-Paraipaba. A variedade estudada foi a anÃo verde do Jiqui. O solo da regiÃo à classificado como Neossolo QuartzarÃnico. O delineamento utilizado foi o de blocos casualisados com quatro repetiÃÃes, totalizando 40 unidades experimentais, com 10 tratamentos, consistindo de cinco doses de nitrogÃnio e cinco de potÃssio combinadas, de acordo com modelo da matriz experimental Plan Puebla III. Foram feitas coletas de solo e das folhas 4 e 9, mediÃÃes da altura, nÃmero de folhas, de folÃolos na folha trÃs, de frutos, de cachos, peso do fruto, volume de Ãgua do fruto, circunferÃncias equatorial e polar e ÂBrix. Com base nos resultados obtidos pela superfÃcie de resposta, foi possÃvel determinar os pontos de mÃxima eficiÃncia de resposta para algumas variÃveis estudadas. A aplicaÃÃo de nitrogÃnio e potÃssio no solo causou efeitos significativos nas caracterÃsticas da planta e do solo estudados. A mÃxima eficiÃncia de resposta para a altura, circunferÃncia do coleto, nÃmeros de folhas, de folÃolos na folha 3, de flores femininas, de frutos, de cachos, em peso do fruto, as circunferÃncias equatorial e polar, o volume de Ãgua do fruto e o ÂBrix, foi verificada no T4 (1260gN e 1680g K2O/planta/ano e de 2100gN e 3500gK2O/planta/ano, com trÃs e quatro anos de idade respectivamente). As aplicaÃÃes de N e K no solo elevaram significativamente para mais os teores de nitrogÃnio e potÃssio nas folhas e no solo. / The dwarfed coconut palm corpping is growing in the Cearà State, due to the great search of the product for the great industries. The objectives of the present study had been to evaluate: a) the effect of different rates of nitrogen and potassium, applied through fertigation, on both growth and production of the cropped dwarfed coconut palm in a sandy soil of the littoral region of the Cearà State, b) to determine the NK leaf (mature plants) critical levels and c) to establish the rates of NK required for the maximum efficiency of crop response under different climate and soil conditions of the region of the Cearà State. The experiment was conducted in a commercial plantation of the dwarfed coconut palm grown by the Embrapa Tropical AgroindÃstria inside a producer exploration area (Latitude 3 17 ' South, Longitude 39 15' West and altitude of 30 meters), in a period from December of 2002 to December of 2003, in Paracuru County (Cearà Satate) close to the Irrigated Perimeter Curu-Paraipaba. The coconut cultivar was the green dwarf of the Jiqui. The soil used in the study was classified as Neossolo QuartzarÃnico. The statistical design folllows a entirely randomized blocks, with four replications, totalizing 40 experimental units, with 10 treatments which consisted of five rates of nitrogen and five of potassium, both combined, in accordance with the model of the experimental Plan Puebla III matrix. Soil samples were collected and also the crop 4rd and 9th leaves; measurements of the height, number of leaves, leafcomposites of the 3rd in leaf, number of fruits, number of clusters, fruit weight, fruit water volume, measures of equatorial and polar circumferences and ÂBrix. On the basis of the obtained results, and observing surface equations, it was possible to determine the points of maximum response for some of the studied variables. The application of nitrogen and potassium in the soil caused significant effects on the characteristics of studied plant and soil variables. The maximum response for the height, for the circumference of the collect, for number of leaves, leafcomposites of the 3rd leaf, for the number of female flowers, for the number of fruit/plant, for the number of clusters, for the fruit weight, for the equatorial and polar circumferences, for the fruit water volume and for the ÂBrix, was of the T4 (1260g and 1680g/plant/year of N and K2O and 2100g and 3500g/plant/year of N, and K2O with three and four years old, respectively). The applications of N and K in the soil significantly raised the nitrogen and potassium levels in the leaves and in the soil.

Mineral nutrients have marked effects on plant health by providing the building blocks for plant growth, as well as for mitigating abiotic and biotic stress factors, particularly disease development. Even if mineral nutrition field studies are conducted to study pest management, they are at the mercy of complex soil, water, and climatic conditions not amenable to strict experimental control. Therefore, a hydroponic method of growing lettuce was developed and growth curves were established for the macronutrients nitrogen (N), phosphorus (P), and potassium (K). Lettuce plants were grown at varying levels of each nutrient: 2.5, 5, 10, 20, 40, 80, 160, and 320 mg N/L; 0.5, 1, 2, 4, 8, 16, 32 and 64 mg P/L; and 0, 2.5, 5, 10, 20, 40, 80 and 160 mg K/L. Due to inadequate results lettuce was grown again at 0, 10, 20, 40, 80, 160, 320 and 640 mg L K. Optimal levels of N, P, and K were 160 mg/L, 4.0 mg/L, and 80 mg/L respectively. C:N ratios were also looked at for the N experiment. The overall result was consistent with results from similar studies. Unlike similar hydroponic studies done with other plants, micronutrient levels did not become deficient at high phosphorus levels suggesting phosphorus toxicity. These growth curves can be used to test lettuce resilience to various biotic and abiotic stresses.

<p>Potassium is an essential nutrient, that has been labeled a shortfall nutrient by recent Dietary Guidelines for Americans Advisory Committees. Increases in potassium intake have been linked to improvements in cardiovascular and other metabolic health outcomes. Blood pressure (BP) has often been cited as the primary criterion for determining potassium requirements. Hypertension (HTN), or high BP, is a primary risk factor for cardiovascular disease and other circulatory diseases. Cardiovascular disease (CVD) is responsible for the 31% of deaths worldwide. Findings from the Agency for Healthcare Research and Quality report (which informed the recently released Dietary Reference Intakes for sodium (Na) and potassium) on potassium intake and chronic disease concluded, with a moderate strength of evidence, that increasing potassium intake decreases BP, particularly among those with HTN. Although, of the 18 randomized controlled trials assessed by the AHRQ, only 4 were dietary interventions, the rest involved potassium supplementation. Observational studies also show a consistent bone benefit with increased potassium rich fruit and vegetable intakes in cohorts spanning adolescents to the elderly. In clinical trials, higher potassium intakes through supplementation have been associated with reduced urinary calcium (Ca) excretion and improvement in Ca balance. Although, similar to BP, intervention trials assessing the impact of dietary potassium on bone are lacking. Controlled feeding studies looking specifically at increases in potassium from food are sparse, leaving a large knowledge gap in the field for a nutrient with an important potential health impact. In general, little is known about whole-body potassium retention, with the few studies conducted lacking consistency and rigor in methods and design. What potassium retention means in terms of adequacy, or how higher or lower retention may influence specific health outcomes is understudied and not well understood. </p> <p>Utilizing a randomized, cross-over, controlled feeding clinical study with complete metabolic balance measures, our research aims to begin filling these gaps, looking specifically at the effects of potassium intake via potato sources and a potassium supplement on BP and vascular outcomes, as well as how the source of potassium may influence potassium, Na and Ca whole-body balance. </p> <p>This dissertation will discuss the physiology of potassium intake, how this may affect potassium, Na, and Ca retention, and in turn what influence this has on vascular and bone related health outcomes. Overall the goal of this research is to address the question: What is the importance of dietary potassium, and how can it benefit cardiovascular and skeletal health?</p>

Sigma receptors have been implicated in the regulation of the cardiovascular system. Some of the cardiovascular effects of sigma receptors may be through the modulation of autonomic neurons. Studies on the expression and cellular function of sigma receptors in autonomic neurons were conducted in neonatal rat intracardiac (ICG) and superior cervical ganglia (SCG). Individual neurons from SCG and ICG were shown to express transcripts encoding the sigma-1 receptor. The effects of sigma receptors activation on high-voltage-activated Ca2+ channels was studied in isolated neurons of these ganglia. Bath application of sigma receptor agonists depressed peak calcium channel currents in a dose-dependent manner and the rank order potency of haloperidol> ibogaine > (+)-pentazocine > DTG is consistent with the effects being mediated by a sigma-2 receptor. Sigma receptor antagonist, metaphit, blocked DTG-mediated inhibition of Ca2+ current. Sigma ligands also altered the biophysical properties of these channels. Activation of sigma receptors reversibly blocked delayed outwardly rectifying potassium channels, large conductance Ca2+-sensitive K+ channels, and the M-current with maximal inhibition >80%. The rank order potency of different sigma ligands suggests that the effect is mediated by sigma-1 receptor. While bath application of sigma ligands depolarized ICG neurons, the number of action potentials (AP) fired by the cells in response to depolarizing current pulses was decreased. Experiments on the signal transduction cascade mediated the inhibition of K+ and Ca2+ channels by sigma ligands showed that the signal transduction pathway does not involve a diffusible cytosolic second messenger or a G-protein. Sigma ligands also modulate voltage-gated Na+ channels (VGSC) in ICG neurons. Bath application of sigma ligands inhibited VGSC current with maximal inhibition >90% and altered the biophysical properties of VGSC. The latency of AP generation during depolarizing current ramp was increased by sigma ligands and this effect is through the inhibition of VGSC. These data suggest that activation of sigma receptors on autonomic neurons modulates voltage-gated Ca2+, K+ and Na+ channels and as a result, the generation of AP is inhibited in these neurons. Sigma receptors are likely altering the cell-to-cell signaling in autonomic ganglia and thus regulating cardiac function by the peripheral nervous system.