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D. Damodar Reddy - One of the best experts on this subject based on the ideXlab platform.
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Potassium Balance and release kinetics under continuous rice wheat cropping system in vertisol
Field Crops Research, 2002Co-Authors: Muneshwar Singh, Vineeta Singh, D. Damodar ReddyAbstract:Abstract In an experiment conducted over 8 years at the research farm of the National Research Centre for Weed Sciences, Jabalpur, we investigated the effects of mineral fertilizer and organic manures on K Balances and non-exchangeable K release kinetics in a Typic Haplustert under a rain-fed rice ( Oryza sativa L.) and irrigated wheat ( Triticum vulgare L.) system. Each year, rice was grown with variable levels of fertilizer N with and without organic manures, while recommended rates of 26 kg P ha −1 and 33 kg K ha −1 were applied to both the crops. Wheat was grown without organic manure but with the same levels of fertilizer N as for rice. The apparent K Balance was measured as the difference between total K added and that removed by the crop. Increasing levels of fertilizer N resulted in an increase in the negative K Balance from 56 kg ha −1 yr −1 (control) to 103 kg ha −1 yr −1 at 90 kg N ha −1 and 156 kg ha −1 at 180 kg N ha −1 . Incorporation of farmyard manure (FYM) or green manure (GM) with fertilizer N reduced the negative K Balance. Repeated extraction of soil with 0.01 M CaCl 2 revealed that continuous cropping for 8 years either without fertilizer N (control) or with 90 kg N ha −1 reduced the cumulative K release. However, the application of 180 kg ha −1 of fertilizer N not only maintained the cumulative K release but also improved it. Incorporation of 5 t FYM or 6 t GM ha −1 with 90 kg N ha −1 resulted in an increase in K release by 58 and 37 mg kg −1 soil, respectively, over the values measured in a soil sample collected at the onset of the experiment. A parabolic diffusion equation described the release rate of the non-exchangeable K. The equation suggested that the application of fertilizer N reduced the release rate of K, whereas the incorporation of manure, with fertilizers, increased it over the values obtained from soil collected at the onset of the experiment. The large cumulative K release at 180 kg N ha −1 was due to the amount of K released initially. Continuous cropping at a fertilizer level of 33 kg K ha −1 may pose a threat to the sustainability of the rice–wheat system. Recycling of crop residue or application of higher levels of fertilizer K may provide long-term sustainability to the system.
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Potassium Balance and release kinetics of non-exchangeable K in a Typic Haplustert as influenced by cattle manure application under a soybean-wheat system
Soil Research, 2002Co-Authors: Muneshwar Singh, A. K. Tripathi, D. Damodar ReddyAbstract:Potassium Balance and non-exchangeable Potassium release in 0.01 M CaCl2 medium in a Typic Haplustert were studied in a 7-year-old soybean–wheat rotational experiment involving 4 levels of cattle manure along with the recommended dose of K (66 kgsha.year). Continuous cropping without returning crop residues to the soil led to a negative Balance of 66–107 kg Ksha.year. Manuring at the rate of 4 and 8 tsha did not significantly change the negative Balance, but application of 16 tsha manure reduced the negative K Balance. Continuous cropping without cattle manure reduced cumulative K release from 236 mgskg (initial) to 195 mgskg. Application of manure at 4, 8, and 16 tsha kept K release at 229, 245, and 246 mgskg soil, respectively. A parabolic diffusion equation was the best fit to describe K release. Cropping under the present level of K input resulted in a decline in non-exchangeable K whatever the addition of manure. Manuring at 4 and 8 tsha has accelerated the mining of native K, which increased the unsustainability of the system. K Balance, non-exchangeable K release kinetics, soybean–wheat rotation, cattle manure, Typic Haplustert.
Bernard C Rossier - One of the best experts on this subject based on the ideXlab platform.
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genetic dissection of sodium and Potassium transport along the aldosterone sensitive distal nephron importance in the control of blood pressure and hypertension
FEBS Letters, 2013Co-Authors: Bernard C Rossier, Olivier Staub, Edith HummlerAbstract:In this review, we discuss genetic evidence supporting Guyton's hypothesis stating that blood pressure control is critically depending on fluid handling by the kidney. The review is focused on the genetic dissection of sodium and Potassium transport in the distal nephron and the collecting duct that are the most important sites for the control of sodium and Potassium Balance by aldosterone and angiotensin II. Thanks to the study of Mendelian forms of hypertension and their corresponding transgenic mouse models, three main classes of diuretic receptors (furosemide, thiazide, amiloride) and the main components of the aldosterone- and angiotensin-dependent signaling pathways were molecularly identified over the past 20 years. This will allow to design rational strategies for the treatment of hypertension and for the development of the next generation of diuretics.
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sodium and Potassium Balance depends on αenac expression in connecting tubule
Journal of The American Society of Nephrology, 2010Co-Authors: Birgitte Monster Christensen, Annie Mercier Zuber, Caroline Ronzaud, Sumedha Malsure, Romain Perrier, Marc Maillard, David Mordasini, Jeanchristophe Stehle, Qing Wang, Bernard C RossierAbstract:Mutations in α, β, or γ subunits of the epithelial sodium channel (ENaC) can downregulate ENaC activity and cause a severe salt-losing syndrome with hyperkalemia and metabolic acidosis, designated pseudohypoaldosteronism type 1 in humans. In contrast, mice with selective inactivation of αENaC in the collecting duct (CD) maintain sodium and Potassium Balance, suggesting that the late distal convoluted tubule (DCT2) and/or the connecting tubule (CNT) participates in sodium homeostasis. To investigate the relative importance of ENaC-mediated sodium absorption in the CNT, we used Cre-lox technology to generate mice lacking αENaC in the aquaporin 2–expressing CNT and CD. Western blot analysis of microdissected cortical CD (CCD) and CNT revealed absence of αENaC in the CCD and weak αENaC expression in the CNT. These mice exhibited a significantly higher urinary sodium excretion, a lower urine osmolality, and an increased urine volume compared with control mice. Furthermore, serum sodium was lower and Potassium levels were higher in the genetically modified mice. With dietary sodium restriction, these mice experienced significant weight loss, increased urinary sodium excretion, and hyperkalemia. Plasma aldosterone levels were significantly elevated under both standard and sodium-restricted diets. In summary, αENaC expression within the CNT/CD is crucial for sodium and Potassium homeostasis and causes signs and symptoms of pseudohypoaldosteronism type 1 if missing.
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collecting duct specific gene inactivation of αenac in the mouse kidney does not impair sodium and Potassium Balance
Journal of Clinical Investigation, 2003Co-Authors: Isabelle Rubera, Johannes Loffing, Lawrence G Palmer, Gustavo Frindt, Nicole Fowlerjaeger, Daniel Sauter, Tom Carroll, Andrew P Mcmahon, Edith Hummler, Bernard C RossierAbstract:Aldosterone controls the final sodium reabsorption and Potassium secretion in the kidney by regulating the activity of the epithelial sodium channel (ENaC) in the aldosterone-sensitive distal nephron (ASDN). ASDN consists of the last portion of the distal convoluted tubule (late DCT), the connecting tubule (CNT), and the collecting duct (CD) (i.e., the cortical CD [CCD] and the medullary CD [MCD]). It has been proposed that the control of sodium transport in the CCD is essential for achieving sodium and Potassium Balance. We have tested this hypothesis by inactivating the α subunit of ENaC in the CD but leaving ENaC expression in the late DCT and CNT intact. Under salt restriction or under aldosterone infusion, whole-cell voltage clamp of principal cells of CCD showed no detectable ENaC activity, whereas large amiloride-sensitive currents were observed in control littermates. The animals survive well and are able to maintain sodium and Potassium Balance, even when challenged by salt restriction, water deprivation, or Potassium loading. We conclude that the expression of ENaC in the CD is not a prerequisite for achieving sodium and Potassium Balance in mice. This stresses the importance of more proximal nephron segments (late DCT/CNT) to achieve sodium and Potassium Balance.
Tahir Hussain - One of the best experts on this subject based on the ideXlab platform.
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role of at2r angiotensin type 2 receptor in maintaining sodium Potassium Balance
Hypertension, 2018Co-Authors: Sanket N Patel, Tahir HussainAbstract:See related article, pp 622–630 Sodium (Na+) Balance is flow dependent and occurs along the nephron because of basic communication between nephron segments in response to Na+ levels and to maintain Na+ delivery to the distal convoluted tubule (DCT).1 Decreased distal Na+ delivery increases Na+ reabsorption by facilitating epithelial Na+ channel activity in the distal nephron at the expense of K+ excretion to maintain the ionic gradient. This process is very dynamic and is affected by multiple factors. Ang-II (angiotensin-II) and its AT1R (ang-II type 1 receptor) constitute a well-known antinatriuretic hormone/receptor system that promotes Na+ reabsorption and decreases distal Na+ delivery. Now, there is ample evidence demonstrating the natriuretic role of the AT2R (angiotensin type 2 receptor) in normal and pathological conditions. Along the nephron, the proximal and distal tubules are the primary sites where AT2R is expressed, albeit at a very low receptor density. However, the expression of renal AT2R increases in pathological conditions, such as obesity and diabetes mellitus, including in the diabetic human kidney. AT2R expressed in the proximal tubule seems to play a significant role in natriuresis potentially via inhibition of sodium transporters, such as the NKA (Na+-K+-ATPase). According to at least 1 study, AT2R-mediated natriuresis is not impacted by inhibitors of the distal tubule transporter NCC (Na+-Cl− cotransporter) and epithelial Na+ channel activity.2 Compared with that discussing the role of AT2R in Na+ excretion, literature describing the effect of AT2R on the K+ channel is limited only to neuronal cells3 and the renal outer medullary K+ channel4 in the cortical collecting duct. Wu et …
H S Gupta - One of the best experts on this subject based on the ideXlab platform.
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Potassium Balance as influenced by farmyard manure application under continuous soybean wheat cropping system in a typic haplaquept
Geoderma, 2006Co-Authors: Ranjan Bhattacharyya, Ved Prakash, S Kundu, B N Ghosh, A K Srivastva, H S GuptaAbstract:Abstract The effect of 30 years of continuous cropping, fertilization and manuring on the Potassium (K) Balances, the soil K pools and the non-exchangeable K release in a Typic Haplaquept soil from Almora, India under a rainfed soybean–wheat cropping system were investigated. The apparent K Balance was measured as the difference between the total K added and that removed by the crops. The results showed that the total removal of K by the crops exceeded the amount of total K applied to the soil in all the treatments showing a net negative K Balance. This ranged from 3.7 in the plots under NK to 81.7 kg ha − 1 year − 1 in the N + FYM treated plots. Continuous annual application of recommended doses of NPK + 10 t FYM (NPK + FYM) to soybean resulted in an accumulation (+ 56 kg K ha − 1 ) of exchangeable K (1 N NH 4 OAc extractable K) in the 0–45 cm soil depth over the study period, despite the highest average annual uptake of K by the system (150.8 kg ha − 1 year −1 ). However, there was a net depletion of exchangeable K (− 80 kg K ha − 1 ) in that soil depth under the NPK treated plots. The results also revealed that the content of non-exchangeable K decreased substantially from 3482 kg ha − 1 to 2677 and 2896 kg ha − 1 in the 0–45 cm soil layer after 30 years of cropping in the plots under NPK + FYM and NPK treatments, respectively. There was a significant decline in total soil K with the removal of non-exchangeable soil K in the surface (0–15 cm) soil layer ( R 2 = 0.526, P n = 36). Thus, long-term application of non-revised recommended fertilizer rates may threaten sustainability of the rainfed continuous soybean–wheat system.
Gilles Crambert - One of the best experts on this subject based on the ideXlab platform.
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Renal proteinase-activated receptor 2, a new actor in the control of blood pressure and plasma Potassium level.
Journal of Biological Chemistry, 2013Co-Authors: Luciana Morla, Sureshkrishna Ramakrishnan, Martine Imbert-teboul, Gaëlle Brideau, Lydie Cheval, Marc Fila, Gilles Crambert, Pascal Houillier, Alain DoucetAbstract:Abstract Proteinase-activated receptor 2 (PAR2) is a G protein-coupled membrane receptor that is activated upon cleavage of its extracellular N-terminal domain by trypsin and related proteases. PAR2 is expressed in kidney collecting ducts, a main site of control of Na+ and K+ homeostasis, but its function remains unknown. We evaluated whether and how PAR2 might control electrolyte transport in collecting ducts, and thereby participate in the regulation of blood pressure and plasma K+ concentration. PAR2 is expressed at the basolateral border of principal and intercalated cells of the collecting duct where it inhibits K+ secretion and stimulates Na+ reabsorption, respectively. Invalidation of PAR2 gene impairs the ability of the kidney to control Na+ and K+ Balance and promotes hypotension and hypokalemia in response to Na+ and K+ depletion, respectively. This study not only reveals a new role of proteases in the control of blood pressure and plasma Potassium level, but it also identifies a second membrane receptor, after angiotensin 2 receptor, that differentially controls sodium reabsorption and Potassium secretion in the late distal tubule. Conversely to angiotensin 2 receptor, PAR2 is involved in the regulation of sodium and Potassium Balance in the context of either stimulation or nonstimulation of the renin/angiotensin/aldosterone system. Therefore PAR2 appears not only as a new actor of the aldosterone paradox, but also as an aldosterone-independent modulator of blood pressure and plasma Potassium.
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Chronic Potassium depletion increases adrenal progesterone production that is necessary for efficient renal retention of Potassium
Kidney International, 2011Co-Authors: Boutaïna Elabida, Amel Salhi, Anie Azroyan, Heidi Fodstad, Pierre Meneton, May Bloch-faure, Alain Doucet, Aurélie Edwards, Gilles CrambertAbstract:Modern dietary habits are characterized by high-sodium and low-Potassium intakes, each of which was correlated with a higher risk for hypertension. In this study, we examined whether long-term variations in the intake of sodium and Potassium induce lasting changes in the plasma concentration of circulating steroids by developing a mathematical model of steroidogenesis in mice. One finding of this model was that mice increase their plasma progesterone levels specifically in response to Potassium depletion. This prediction was confirmed by measurements in both male mice and men. Further investigation showed that progesterone regulates renal Potassium handling both in males and females under Potassium restriction, independent of its role in reproduction. The increase in progesterone production by male mice was time dependent and correlated with decreased urinary Potassium content. The progesterone-dependent ability to efficiently retain Potassium was because of an RU486 (a progesterone receptor antagonist)-sensitive stimulation of the colonic hydrogen, Potassium–ATPase (known as the non-gastric or hydrogen, Potassium–ATPase type 2) in the kidney. Thus, in males, a specific progesterone concentration profile induced by chronic Potassium restriction regulates Potassium Balance.