Role Of Potassium Research Articles

Considerations of the technological quality assessment of sugarbeet

No real improvement in the technological quality of beet has been recorded over the last 15 years in Northern Italy. Among the possible explanations for the quality stagnation is that the traditional formulae cannot correctly differentiate between sugarbeet varieties which produce thick juice of very high purity. This seems to be connected with the role of potassium. The use of a standard purification procedure gives reliable and accurate data which is immediately comparable with the factory data. Research projects on medium/long term storage are currently being performed by Co.Pro.B., Italy, in cooperation with Syngenta and Beta. Up to now the results have shown that storage of sugarbeet in autumn time in northern Italy is possible provided that suitable varieties and proper handling of the roots are employed. Results obtained in the storage trials are reported. Correlations have been found between quality parameters (purity, color and lime salts) of the purified juice with the glucose content of the raw juice. An interesting correlation is reported between purified juice purity and raw juice purity.

Effects of Potassium on the Supramolecular Structure and Electronic Properties of Eumelanin Thin Films

The role of potassium in the formation of synthetic eumelanin aggregates is investigated by atomic force microscopy and soft-X-ray spectroscopy. Control over the thin film granularity is achieved by using K salts, in both drop casting and electrodeposition of eumelanin thin films. Further control over orientation is made possible by a suitable choice of the substrate: evidence of self-assembly is found for thin films deposited on gold. Finally, it is shown that the potassium content affects not only the samples morphology, but also the low-lying states in the valence band, where a transfer of spectral weight across the HOMO-LUMO gap is observed, disclosing possible applications of this multifunctional biomacromolecule.

Photoelectron spectroscopy for probing surface reactions at the CO/K/Cu(1 1 5) interface

The adsorption of carbon monoxide on the potassium modified Cu(1 1 5) surface was investigated using photoelectron spectroscopy based on synchrotron radiation. From detailed analysis of the 1 s core levels in combination with existing knowledge, the assignment of surface species is performed. It is demonstrated that in dependence of the alkali coverage, several adsorption states of CO are present on the interface at 135 K. From the temperature dependence of the C 1 s and O 1 s profiles it is established that surface reactions based on CO dissociation start from 223 K over an interface with a potassium coverage close to half a complete K overlayer. The role of potassium as a reordering environment of adsorbed CO, leading to molecule dissociation and disproportionation is proposed. It is observed that a higher density of potassium on the substrate surface blocks adsorption sites for incoming CO molecules and no dissociation takes place.

The renal H,K-ATPases

We integrate recent evidence that demonstrates the importance of the gastric (HKalpha1) and nongastric (HKalpha2)-containing hydrogen potassium adenosine triphosphatases (H,K-ATPases) on physiological function and their role in potassium (K), sodium (Na), and acid-base balance. Previous studies focused on the primary role of H,K-ATPases as a mechanism of K conservation during states of K deprivation. Both isoforms function in H secretion and K absorption in vivo during K deprivation, but recent findings show that these pumps also function in acid secretion in animals fed normal K-replete diets. The complicated pharmacological inhibition of both pumps is reviewed. Interestingly, HKalpha2-null mice have a reduced expression and activity of the renal epithelial Na channel alpha subunit in the colon. When the human nongastric isoform was studied in a heterologous expression system with its cognate beta subunit (NaKbeta1), the pump exhibited substantial Na affinity at the 'K'-binding site. Evidence cited herein raises the possibility that either directly or indirectly the renal HKalpha2-containing H,K-ATPase may affect Na balance. Both H,K-ATPase isoforms are active in normal animals and not just under conditions of K depletion. The possibility that either one or both isoforms contribute to Na absorption, particularly in humans, raises important clinical implications for these pumps in the kidney.

Potassium for better crop production and quality

Increasing crop production while improving quality remains an important goal, particularly in the developing world. Significant increases in food prices and growing economic crises have a major impact on nutritional status of human populations and exacerbate global malnutrition. These developments make nutrient security together with food security a key global challenge. Among many factors, an adequate and well balanced nutrition with mineral nutrients is a fundamental issue in achieving a high crop production and a better quality in practical agriculture. Of the mineral nutrients, imbalanced nutrition with potassium (K) is well known and becoming an important constraint to crop production in the developing countries. Very low rates of potash fertilizer application in agricultural production in India and other developing countries lead to rapid depletion of K in the soil. Depletion of plant-available K in soils results in a variety of negative impacts, including preventing optimum utilization of applied nitrogen and phosphorus fertilizers, decreasing farmers’ income, threatens the yields of the cropping systems (e.g., wheat-rice cropping systems) and hence jeopardizes the future food and nutrient security. Indian growers and their advisors need to adopt advanced tools for potash fertilizer applications and updated K recommendations by considering nutrient management practices based on the latest scientific findings. Currently, there is increasing evidence for the diverse functions of K from the molecular level to field performance. The role of K in stress signaling is becoming an important topic (Amtmann et al. 2008; Wang and Wu 2010) that needs to be addressed increasingly in future research by molecular biologists, plant physiologists and agronomists. The stressmitigating role of K is another role in plants, particularly under drought, salinity, and upon pathogenic infection (Cakmak 2005; Amtmann et al. 2008). An adequate K nutrition is also of great importance for the composition of harvested products and the quality of diet. In addition, impaired nutrient management and related nutrient inputoutput imbalances, especially with K, may represent a serious issue in forest nutrition and wood production (Ache et al. 2010). The Potassium Symposium entitled “Potassium Role and Benefits in Improving Nutrient Management for Food Production, Quality and Reduced Environmental Damages” was organized in order to discuss and analyze the issues described above. The papers given in this Special Issue focus on the role of potassium and other mineral nutrients in cropping systems, nutrient-use efficiency, food production and quality, forest nutrition, and climatic changes. This Potassium Symposium provided an excellent opportunity Plant Soil (2010) 335:1–2 DOI 10.1007/s11104-010-0534-8

Special lecture III: The role of potassium and sodium channels in renal tubule electrolyte transport

Special lecture III: The role of potassium and sodium channels in renal tubule electrolyte transport

RESPONSES OF LABLAB PURPUREUS (L.) SWEET / RHIZOBIUM SYMBIOSIS AND GROWTH TO POTASSIUM SUPPLY UNDER DIFFERENT WATER REGIMES

A pot experiment was executed in sandy clay loam soil collected from Toshka region in south of Egypt to investigate the role of potassium (K) fertilization on nodulation, dinitrogen (N2) fixation, protein, and leghaemogloin contents of nodule cytosol and growth in water-stressed Lablab purpureus (L.) Sweet Kashrangeeg. The obtained results indicate that an adequate supply of K can help to maintain efficient Lablab purpureus/Rhizboium symbioses despite a severe water deficiency.

The Role of Potassium in Inflammasome Activation by Bacteria

Many Gram-negative bacteria possess a type III secretion system (TTSS¶) that can activate the NLRC4 inflammasome, process caspase-1 and lead to secretion of mature IL-1β. This is dependent on the presence of intracellular flagellin. Previous reports have suggested that this activation is independent of extracellular K+ and not accompanied by leakage of K+ from the cell, in contrast to activation of the NLRP3 inflammasome. However, non-flagellated strains of Pseudomonas aeruginosa are able to activate NLRC4, suggesting that formation of a pore in the cell membrane by the TTSS apparatus may be sufficient for inflammasome activation. Thus, we set out to determine if extracellular K+ influenced P. aeruginosa inflammasome activation. We found that raising extracellular K+ prevented TTSS NLRC4 activation by the non-flagellated P. aeruginosa strain PA103ΔUΔT at concentrations above 90 mm, higher than those reported to inhibit NLRP3 activation. Infection was accompanied by efflux of K+ from a minority of cells as determined using the K+-sensitive fluorophore PBFI, but no formation of a leaky pore. We obtained exactly the same results following infection with Salmonella typhimurium, previously described as independent of extracellular K+. The inhibitory effect of raised extracellular K+ on NLRC4 activation thus reflects a requirement for a decrease in intracellular K+ for this inflammasome component as well as that described for NLRP3.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Potassium‐dependent wood formation in poplar: seasonal aspects and environmental limitations

Potassium availability and acquisition are pivotal for the generation of biomass and thus wood formation in growing poplar trees. Here, we focus on the role of potassium (K(+)) in wood production, transitions between dormancy and active growth, and limiting environmental conditions. Molecular mechanisms, such as expression and activity of K(+) transporters and channels controlling seasonal changes in wood formation, are discussed.

POTASSIUM AND MAGNESIUM DRUGS IN THE TREATMENT OF CARDIOVASCULAR DISEASES IN THE PRACTICE OF PRIMARY CARE PHYSICIAN

Role of magnesium and potassium deficiency in the development of cardiovascular diseases and their complications is discussed. Results of studies on efficacy of magnesium and potassium drugs in cardiology practice are presented. Preventive role of potassium and magnesium in the progression of atherosclerosis, arterial hypertension, endothelial dysfunction and insulin resistance is shown. The advantages of combined magnesium and potassium drugs are shown.

Potassium Level and Physiological Response and Fruit Quality in Hydroponically Grown Tomato

Tomato (Lycopersicon esculentum Mill.) is a popular vegetable in many parts of the world. The role of potassium in plant metabolism, growth, and development and its significance in production of marketable fruit and on fruit flavor and visual appearance are known. It is not clear how hybrids and nonhybrids, which differ greatly in growth and yield, respond to potassium. The tomato cvs. Pant T-3 (nonhybrid) and Avinash-2 (hybrid) were treated with three levels of potassium at 200, 300, and 400 mg·L−1 in Hoagland nutrient solution culture. ‘Avinash-2’ produced more fruit than the nonhybrid cv. Pant T-3. Fruit production increased as potassium concentration increased in both cvs., but magnitude of yield was greater for the nonhybrid cultivar. The highest leaf chlorophyll content, photosynthetic rate, and potassium contents were in plants treated with 300 mg·L−1 K in both cultivars. There was significant improvement in protein, ascorbic acid, lycopene, total soluble solids, reducing sugar levels, and titratable acidity in fruit as K concentration increased up to 300 mg·L−1. The cv. Pant T-3 responded better to K concentration than did ‘Avinash-2’. Application of adequate potassium is necessary to improve yield and quality of tomato and K availability had a role in improving fruit production and quality of a nonhybrid tomato more so than in a hybrid tomato cultivar.

Sp1trans-activates the murine H+-K+-ATPase α2-subunit gene

The H(+)-K(+)-ATPase alpha(2) (HKalpha2) gene of the renal collecting duct and distal colon plays a central role in potassium and acid-base homeostasis, yet its transcriptional control remains poorly characterized. We previously demonstrated that the proximal 177 bp of its 5'-flanking region confers basal transcriptional activity in murine inner medullary collecting duct (mIMCD3) cells and that NF-kappaB and CREB-1 bind this region to alter transcription. In the present study, we sought to determine whether the -144/-135 Sp element influences basal HKalpha2 gene transcription in these cells. Electrophoretic mobility shift and supershift assays using probes for -154/-127 revealed Sp1-containing DNA-protein complexes in nuclear extracts of mIMCD3 cells. Chromatin immunoprecipitation (ChIP) assays demonstrated that Sp1, but not Sp3, binds to this promoter region of the HKalpha2 gene in mIMCD3 cells in vivo. HKalpha2 minimal promoter-luciferase constructs with point mutations in the -144/-135 Sp element exhibited much lower activity than the wild-type promoter in transient transfection assays. Overexpression of Sp1, but not Sp3, trans-activated an HKalpha2 proximal promoter-luciferase construct in mIMCD3 cells as well as in SL2 insect cells, which lack Sp factors. Conversely, small interfering RNA knockdown of Sp1 inhibited endogenous HKalpha2 mRNA expression, and binding of Sp1 to chromatin associated with the proximal HKalpha2 promoter without altering the binding or regulatory influence of NF-kappaB p65 or CREB-1 on the proximal HKalpha2 promoter. We conclude that Sp1 plays an important and positive role in controlling basal HKalpha2 gene expression in mIMCD3 cells in vivo and in vitro.

Coronatine‐induced lateral‐root formation in cotton (Gossypium hirsutum) seedlings under potassium‐sufficient and ‐deficient conditions in relation to auxin

AbstractA large root system plays a decisive role in potassium (K)‐acquisition efficiency of cotton. Coronatine (COR), a non‐host‐specific phytotoxin, may affect the auxin level in plants and might therefore be useful in regulating lateral‐root (LR) development. Our objectives were (1) to examine the effects of COR on root development, especially the LR formation in hydroponically grown cotton seedlings, and (2) to explore possible mechanisms involved. The results showed that K deficiency (0.05 mM) significantly reduced LR formation in cotton seedlings, possibly due to the decrease of endogenous indole acetic acid (IAA) in roots by more than half. Following the application of 10 nM COR, the LRs significantly increased by 26% in K‐sufficient (0.5 mM) solution and by 95% in K‐deficient solution. Although COR did not increase the free IAA level in the primary root, the polar auxin‐transport inhibitor N‐1‐naphthylphthalamic acid (NPA) decreased its stimulating effects on LR formation by 25%–30%, suggesting that the COR‐induced LR formation was independent of increased auxin level but likely associated with auxin transport. Treatment of plants with 1‐naphthalene acetic acid (NAA) increased LR formation at NAA concentrations of 100 nM, but had no effect at 10 nM. In the presence of 1 nM COR, however, NAA increased LR formation at 10 nM concentrations. This indicates that LR formation due to COR possibly involves changes in auxin sensitivity. In addition, the shorter LRs of COR‐treated seedlings were clearly restored when COR was removed from solutions for 12 d, and the total root length, total root surface area as well as K uptake increased significantly, suggesting that COR may be potentially useful for enhancing the K‐acquisition efficiency of cotton seedlings.

Relation of Baseline Serum Potassium Levels to Angiographic Findings in Patients With Known or Suspected Coronary Artery Disease

In experimental animal studies, potassium has been demonstrated to protect against the development of atherosclerosis through a variety of mechanisms. Data regarding the role of potassium in the development of human atherosclerosis are sparse. The objective of this study was to determine the association between plasma potassium levels and angiographically defined coronary artery disease (CAD). In a cohort of 389 male patients undergoing coronary angiography for a variety of clinical indications, the association between baseline serum potassium levels and the extent of angiographically defined atherosclerosis was analyzed. Adjustments were made for clinical and laboratory variables (including inflammatory markers) known to be associated with atherosclerosis. By multivariate logistic regression analysis, baseline serum potassium levels were an independent predictor of the presence of multivessel disease (odds ratio (OR) 1.31, 95% confidence interval (CI) 1.01-1.69; P < 0.05). In addition, in the non-myocardial infarction subpopulation of patients, serum potassium was also an independent predictor of the presence of multivessel disease by multivariate logistic regression analysis (OR 1.34, 95% CI, 1.02-1.76; P < 0.05). In the myocardial infarction (MI) subpopulation, serum potassium was not a predictor of multivessel disease, possibly due to the confounding effect of hypokalemia known to be present during MI. These data demonstrate that a simple baseline serum potassium level is independently associated with the presence of multivessel disease, even in the context of clinical CAD risk factors and other established inflammatory markers.

Immunocytochemical Traits of Type IV Fibrocytes and Their Possible Relations to Cochlear Function and Pathology

One of the more consistent and least understood changes in the aging human cochlea is the progressive loss of fibrocytes within the spiral ligament. This report presents an animal model for type IV fibrocyte loss, along with immunocytochemical evidence that noise-induced loss of these cells may account for previously unexplained hearing losses. The remarkably low threshold for noise-induced loss of type IV fibrocytes, approximately 24 dB less than the threshold for adjacent hair cell destruction, may account for the prevalence of missing fibrocytes in humans. In mice, changes in the spectrum of traumatizing noise had little effect upon the site of loss of the fibrocytes, suggesting that the primary site of damage that induced the loss was the basal-most cochlear turn, a site expected to be damaged by all three noise bands. Type IV fibrocytes were found to immunostain for connective tissue growth factor (CTGF) and for transforming growth factor beta receptor 3, a receptor that is known to activate CTGF expression. Type IV fibrocytes lack immunostaining for adenosine triphosphatase and connexins that are key players in potassium ion uptake and transmission, which suggests that they play little, if any, role in potassium recycling from perilymphatic space to the endolymphatic space. Consequently, their loss probably does not directly reduce this process. Immunostaining for a receptor for CTGF, low-density-lipoprotein-related protein 1, indicated that CTGF acts as an autocrine and a paracrine agent within the cochlea. The lack of CTGF paracrine effects following noise-induced loss of type IV fibrocytes may account for previously unexplained hearing losses.

Arrhythmias and Hemodialysis: Role of Potassium and New Diagnostic Tools

Cardiovascular diseases represent the main causes of death in patients affected by renal failure, and arrhythmias are frequently observed in patients undergoing hemodialysis. Dialytic treatment per se can be considered as an arrhythmogenic stimulus; moreover, uraemic patients are characterized by a “pro-arrhythmic substrate” because of the high prevalence of ischaemic heart disease, left ventricular hypertrophy and autonomic neuropathy. One of the most important pathogenetic element involved in the onset of intra-dialytic arrhythmias is the alteration in electrolytes concentration, particularly calcium and potassium. It may be very useful to monitor the patient's cardiac activity during the whole hemodilaytic session. Nevertheless, the application of an extended intradialytic electrocardiographic monitoring is not simple because of several technical and structural impairments. We tried to overcome these difficulties using Whealthy®, a wearable system consisting in a t-shirt composed of conductors and piezoresistive materials, integrated to form fibers and threads connected to tissutal sensors, electrodes, and connectors. ECG and pneumographic impedance signals are acquired by the electrodes in the tissue, and the data are registered by a small computer and transmitted via GPRS or Bluetooth.

Cooperative Effect of Sodium and Potassium Cations on Synthesis of Ferrierite

Ferrierite type zeolite can be synthesized without using any organic structure-directing agent from Na- or (Na, K)- or K-aluminosilicate system. (Na, K)-ferrierite is synthesized from wide range of OH/SiO2 region of the reactant mixture compared with Na- and K-ferrierite. The crystallization process of ferrierite in each system is investigated in detail by X-ray diffraction and Raman spectroscopy. The role of potassium and sodium cations and cooperative effect of two cations in the formation of the framework of ferrierite are elucidated.

A mathematical model for growth and osmoregulation in halophilic bacteria

Many molecular details of the ecophysiology of halophilic bacteria that use compatible solutes to maintain osmotic equilibrium have been examined. We ask whether the details are consistent and complete enough to predict growth and osmoregulation in these bacteria by integrating this information in a mathematical model. Parameterized for the halophilic organism Halomonas elongata, the model predicts the substrate and salt dependence of growth, the uptake of potassium and ectoine and the synthesis of ectoine. It is shown that salt (NaCl) dependence of growth can be modelled by substrate inhibition kinetics. Osmoregulation is known to involve accumulation of both ectoine and potassium glutamate in H. elongata. Using published and newly determined parameters, osmoregulatory models using either direct turgor or two-step (turgor and potassium) signalling are compared. The results are consistent with a role for potassium as a second messenger for hyperosmotic stress. Simulations of osmotic upshifts show a transient overregulation of the intracellular solute levels, as has been previously observed in experiments. A possible adaptive value of this overregulation as 'pre-emptive' behaviour in an environment with frequent dry periods leading to steadily increasing osmolarity is proposed. As a result of growth parameter estimation, a maximum P : O value of 2 for H. elongata can be inferred. In conclusion, the model developed here reproduces essential aspects of growth and osmoregulation in halophilic bacteria with a minimal set of assumptions.

Diffusive Coupling and Network Periodicity: A Computational Study

Diffusive coupling (nearest-neighbor coupling) is the most common type of coupling present in many systems. Previous experimental and theoretical studies have shown that potassium lateral diffusion coupling (i.e., diffusive coupling) can be responsible for synchronization of neuronal activity. Recent in vivo experiments carried out with anesthetized rat hippocampus suggested that the extracellular potassium could play an important role in the generation of a novel type of epileptiform nonsynaptic activity. Yet, the role of potassium in the generation of seizures remains controversial. We tested the hypothesis that potassium lateral diffusion coupling is responsible for the coupling mechanisms for network periodicity in a nonsynaptic model of epilepsy in vivo using a CA1 pyramidal neuron network model The simulation results show that 1), potassium lateral diffusion coupling is crucial for establishing epileptiform activity similar to that generated experimentally; and 2), there exists a scaling relation between the critical coupling strength and the number of cells in the network. The results not only agree with the theoretical prediction, but strongly suggest that potassium lateral diffusion coupling, a physiological realization of the concept of diffusive coupling, can play an important role in entraining periodicity in a nonsynaptic neural network.