Effect Of Potassium Concentration Research Articles

MOISTURE LIMITS AND POTASSIUM CONCENTRATIONS IN THE SOIL SOLUTION FOR CULTIVATION OF LISIANTHUS (Eustoma grandiflorum) FERTIGATED UNDER PROTECTED ENVIRONMENT CONDITIONS

Lisianthus (Eustoma grandiflorum) has been attracting great interest due to the beauty of the colors of flowers, the firmness of stems, and postharvest durability. However, knowledge of lisianthus irrigation and fertigation has generally been based on recommendations from other countries. This study aimed to establish parameters for the rational management of lisianthus fertigation under a protected environment by determining the best lower limit of soil moisture, associated with the determination of the optimal potassium concentration to be maintained in the soil solution. The treatments consisted of five soil moisture limits for the start of irrigation and maintenance of five potassium concentrations in the soil solution, with four replications. Plots of 0.7 by 0.5 m were arranged in a completely randomized block design in a factorial scheme. The soil solution was monitored by measuring moisture as well as potassium (K+) concentrations using a TDR100 reflectometer and solution extractors, respectively, during two cycles. The evaluated variables were the leaf area index, shoot fresh and dry matter, commercial yield, and average stem diameter. Lisianthus cultivation under the lower limit of soil moisture equal to 0.20 cm3 cm−3 ensured the best results for all variables of commercial interest. No effect of potassium concentrations was observed on variables of commercial interest.

Effect of Potassium Concentration on Triplex Stability under Molecular Crowding Conditions.

The properties of non-canonical DNA structures, like G-quadruplexes and triplexes, change under cell-mimicking molecular crowding conditions relative to dilute aqueous solutions. The analysis of environmental effects on their stability is crucial since they play important roles in gene expression and regulation. In this study, three intramolecular and intermolecular triplex-forming sequences of different C+*G-C triplet content (*: Hoogsteen base pair; - : Watson–Crick base pair) were designed and their stability measured in the absence and presence of a crowding agent with different K+ concentrations. In dilute solution, the stability of the triplexes was reduced by decreasing the concentration of KCl. This reduction became smaller as the number of C+*G-C triplets increased. Under molecular crowding conditions, Watson–Crick base pairs and Hoogsteen base pairs were destabilized and stabilized, respectively. Interestingly, with lower KCl concentrations (≤1 M), the destabilization of the triplexes due to reduction of KCl concentration was significantly smaller than in dilute solutions. In addition, the C+*G-C content had greater influence on triplex stability under molecular crowding conditions. Our work provides quantitative information about the effects of K+ concentration on triplex stability under molecular crowding conditions and should further our understanding of the function and regulation of triplexes in bioprocesses.

The influence of KCl on biomass ash melting behaviour and high-temperature corrosion of low-alloy steel

The main aim of this work was to determine the influence of KCl-rich ash deposits on 10CrMo9-10 steel oxidation rate. Two agricultural biomass samples: oat and rye straw, clean and doped with KCl were tested in this study. The addition of KCl does not decrease the melting temperature of the ash when KCl is not incorporated with mineral matter components.Corrosion experiments were performed at 550 °C and 600 °C, with corrosion coupons covered with real and synthetic biomass ash under oxidising conditions. The nonuniform distribution of KCl in ash affected the results and the effect of potassium concentration on oxidation rate was not observed in all cases. More severe influence of ash rich in KCl was observed at lower temperature, the reason is lower protective oxide scale formation rate and higher influence of ashes on steel material and scale.The temperature increase by 50 °C doubled the corrosion rate. At 550 °C KCl was most aggressive salt, but at 600 °C the influence of eutectic mixture KCl+K2SO4 was the highest. Even at lower temperature thermal decomposition of K2CO3 was observed affecting the results. It might be concluded that temperature and eutectic mixture formation are essential parameters in corrosion prediction.

A facile one-pot hydrothermal synthesis as an efficient method to modulate the potassium content of cryptomelane and its effects on the redox and catalytic properties

Cryptomelane has been widely applied as catalyst in oxidation reactions due to its excellent redox properties and low cost. Here, a novel one-pot hydrothermal synthesis using a potassium permanganate aqueous solution as precursor and ethanol as reducing agent has successfully been developed to obtain cryptomelane nano-oxides. This synthetic route makes it possible to control the amount of potassium incorporated into the structure of the cryptomelane by selecting the appropriate synthesis temperature and ethanol initial concentration. Taking advantage of this approach, the effect of potassium concentration on the structural stability and reducibility of the cryptomelane, which are poorly discussed in the literature, has been studied. We have observed that samples with low content of potassium (∼11%) show high conversions of CO to CO2 especially at low temperatures. The lower activity of the samples with high K contents (∼16%) can be ascribed to the beneficial effect of K on the structural stability of cryptomelane in detriment of labile oxygen on cryptomelane surface.

Effect of potassium concentration on the structure and electrical properties of lead-free Bi 0.5 (Na,K) 0.5 TiO 3–BiAlO 3 piezoelectric ceramics

In this study, lead-free 0.975[Bi 0.5(Na 1− x K x ) 0.5TiO 3]–0.025BiAlO 3 piezoelectric ceramics (BNKT–BA) with x ranging from 0 to 0.25 were fabricated using a conventional solid state reaction. The effects of potassium concentration ( x) on the structure and electrical properties of the ceramics were investigated. The X-ray diffraction patterns revealed that the addition of K + improved the crystal symmetry of the BNKT–BA ceramics and produced a rhombohedral–tetragonal morphotropic phase boundary (MPB) in the range of 0.15 ≤ x ≤ 0.20. The increase of the K + concentration resulted in a decreased grain growth rate and promoted the formation of grains with a cubic shape. The BNKT–BA ceramics exhibited high remanent polarizations of 25 μC/cm 2 near the rhombohedral side of the MPB composition ( x = 0.15). The polarization and strain hysteresis loops demonstrated that an increased K + concentration ( x ≥ 0.20) destabilized the ferroelectric order of the BNKT–BA ceramics, leading to degradation of the remanent polarization and coercive field. However, the destabilization of the ferroelectric order was accompanied by significant enhancements in the bipolar and unipolar strains. A large electric field-induced strain ( S = 0.33%) and a corresponding normalized strain ( d 33 * = S max / E max = 533 pm / V ) were obtained on the tetragonal side of the MPB composition ( x = 0.22).

Effects of Potassium Concentration on Firing Patterns of Low‐Calcium Epileptiform Activity in Anesthetized Rat Hippocampus: Inducing of Persistent Spike Activity

It has been shown that a low-calcium high-potassium solution can generate ictal-like epileptiform activity in vitro and in vivo. Moreover, during status epileptiform activity, the concentration of [K+]o increases, and the concentration of [Ca2+]o decreases in brain tissue. Therefore we tested the hypothesis that long-lasting persistent spike activity, similar to one of the patterns of status epilepticus, could be generated by a high-potassium, low-calcium solution in the hippocampus in vivo. Artificial cerebrospinal fluid was perfused over the surface of the exposed left dorsal hippocampus of anesthetized rats. A stimulating electrode and a recording probe were placed in the CA1 region. By elevating K+ concentration from 6 to 12 mM in the perfusate solution, the typical firing pattern of low-calcium ictal bursts was transformed into persistent spike activity in the CA1 region with synaptic transmission being suppressed by calcium chelator EGTA. The activity was characterized by double spikes repeated at a frequency approximately 4 Hz that could last for >1 h. The analysis of multiple unit activity showed that both elevating [K+]o and lowering [Ca2+]o decreased the inhibition period after the response of paired-pulse stimulation, indicating a suppression of the after-hyperpolarization (AHP) activity. These results suggest that persistent status epilepticus-like spike activity can be induced by nonsynaptic mechanisms when synaptic transmission is blocked. The unique double-spike pattern of this activity is presumably caused by higher K+ concentration augmenting the frequency of typical low-calcium nonsynaptic burst activity.

The Effect of Potassium Concentration in Inland Saline Water on the Growth and Survival of the Western King Shrimp, Penaeus latisulcatus Kishinouye, 1896

The survival, growth, and condition of the western king shrimp, Penaeus latisulcatuswere measured for 42 days when grown in marine water and inland saline water with four different concentrations of potassium: 100%, 80%, 60% or 40% of the concentration of potassium in marine water (IS100, IS80, IS60, and IS40). Shrimp survival and cannibalism frequency decreased with decreasing potassium concentration, with final shrimp survival in IS100 significantly higher (P < 0.05) than in IS60 and IS40 and significantly higher (P < 0.05) in MW and IS80 than in IS40. Specific growth rate (SGR), moult increment, and diet ingestion rate of shrimp were significantly higher (P < 0.05) in shrimp grown in marine water than the other water types. At the conclusion of the trial, exoskeleton mineral content of shrimp in IS100 and IS80 was significantly higher (P < 0.05) than in IS60 and IS40. Tail muscle moisture content of shrimp in IS60 and IS40 was significantly higher (P < 0.05) than in the other water types, suggesting a depletion of tail muscle energy reserves in IS60 and IS40. This trial demonstrates the necessity of fortifying potassium-deficient inland saline water to allow the culture of western king shrimp. Furthermore, a potassium concentration greater than approximately 76% of that in marine water and a Na/K ratio of less then 39 appear to be necessary to maintain a comparable level of shrimp survival, as in marine water. However, the slower growth and reduced molt increment of shrimp in inland saline water with 100% and 80% potassium compared to shrimp in marine water demonstrates the presence of other limiting factors.

The Effect of Potassium Concentration on Glycolysis in High and Low Potassium Dog Erythrocytes

The effect of potassium concentration on glycolysis was studied in the erythrocytes of Japanese Shiba dogs with high potassium (HK) and low potassium (LK) concentrations. When intracellular Na and K concentrations were changed in intact erythrocytes, lactate formation increased with increasing K concentration in both HK and LK dogs. In the reconstituted haemolysates, lactate formation, phosphofructokinase (PFK) and pyruvate kinase (PK) activities increased with increasing K concentration in both HK and LK dogs. These results suggest that glycolysis in erythrocytes of HK and LK dogs is dependent on K concentration because PFK and PK require K for their activities. In the reticulocytes of a LK dog possessing high K and low Na concentrations, PK and PFK activities were markedly elevated from the levels in mature erythrocytes and also dependent on K concentration. As in HK dog erythrocytes, high K concentration is required for glucose metabolism in LK dog reticulocytes. It is suggested that the glycolytic system of LK dog erythrocytes retains the potential to be stimulated with high K concentration even after cell maturation.

ドープタングステン細線の高温クリープ中のしきい応力に及ぼすカリウム濃度の影響

ドープタングステン細線の高温クリープ中のしきい応力に及ぼすカリウム濃度の影響

The Effect of Potassium Concentration on Glycolysis and Pyruvate Kinase in High Potassium and Low Potassium Possum Erythrocytes

The Effect of Potassium Concentration on Glycolysis and Pyruvate Kinase in High Potassium and Low Potassium Possum Erythrocytes

The effect of potassium concentration on glycolysis and pyruvate kinase in high potassium and low potassium possum erythrocytes

Effects of potassium concentrations on glycolytic rate and pyruvate kinase (PK) activity were investigated in high potassium (HK) and low potassium (LK) erythrocytes from the common brushtail possum (Trichosurus velpecula). Increasing concentrations of potassium resulted in an increase in glycolytic rate and PK activity in both HK and LK possum erythrocytes. Our results are similar to those from HK/LK sheep. We conclude that there is a close link between Na-pump and glycolysis in erythrocytes from sheep and possum.

Effect of potassium concentration in dialysate on total body potassium

Objective: To investigate the effects of the presence/absence of potassium in the dialysate on total body potassium content in stable hemodialysis patients. Design: Randomized selection. Setting: Outpatient chronic hemodialysis unit at the James A. Haley VA Hospital in Tampa, Florida. Patients: Six adult hemodialysis patients (mean age 48 ± 11.61 years, range 32–65 years) participated in this study. They were all males, four African-Americans and two Caucasians. Intervention: Subjects in a random order received dialysis using a dialysate containing no potassium for 3 months, followed by a 2 mEq/L of potassium for another 3 months. Total body potassium measurements and routine blood analysis were taken at baseline and after each three month period. All subjects received diet instruction pre and monthly on a 3 g/day potassium dietary restriction. Main outcome measured: There were no significant differences in the amount of total body potassium concentration between the two different dialysates containing 0 or 2 mEq/L potassium. Mean values of serum albumin were significantly higher when the subjects were dialyzed on a 0 potassium bath. Conclusion: The use of dialysate containing 0 or 2 mEq/L potassium concentration does not make a significant difference with regard to total body potassium concentration and maybe advantageous for the patients in terms of more freedom in nutritional intake as demonstrated by a significant increase in serum albumin when they were dialyzed on a 0 potassium bath.

Effects of Potassium Concentration and Induced Stress on the Refractive Index Profile of K+-Na+Ion-exchanged Glass Waveguides

Abstract An extensive investigation into the optical properties of K+-Na+ ion-exchanged waveguides in soda-lime glass over a wide range of time and temperature is described. From accurate measurements of effective indices, refractive-index profiles and birefringence are obtained, and by use of microalytical techniques (RBS, EDX) ion concentration profiles are measured. Comparison of these profiles allows a quantitative separation of the compositional and the stress optical contributions to the overall change in refractive index; the time behaviour of stress thermal relaxation processes explains the evolution of the profile shape.

Effect of potassium concentration and ouabain on the renal adaptation to potassium depletion in isolated perfused rat kidney.

Renal adaptation for potassium (K) conservation has been demonstrated in isolated perfused kidneys from rats within 3 days of K depletion and appears to be independent of aldosterone and sodium excretion. This study was designed to investigate whether the renal adaptation for K conservation is independent of ambient [K] and renal tissue levels of K and whether ouabain may have effects on K excretion, which are in contrast to the effects on K excretion in normal animals. In the first study, rats K depleted for 3 days received 2500 mu equiv. KCI intraperitoneally, while other K-depleted rats and a group of control diet animals received intraperitoneal H2O alone to determine whether simple restoration of K deficits would reverse the renal adaptation for K conservation. Intraperitoneal KCI increased plasma [K] and kidney tissue K significantly within 3 h in the K-repleted group compared with the K-depleted rats. Isolated Kidneys were perfused from the three groups of rats 3 h after intraperitoneal injection. Despite K repletion in vivo, perfused kidneys from the K-repleted group still had significantly decreased K excretion (1.28 +/- 0.085 mu equiv./min) compared with controls (2.05 +/- 0.291 mu equiv./min), and K excretion was still not different from the K-depleted group (0.57 +/- 0.134 mu equiv./min). However, fractional K excretion by the kidneys from K-repleted rats was increased above K-depleted kidneys (0.48 +/- 0.051 vs. 0.18 +/- 0.034, p less than 0.01). Despite the increased renal tissue K in K-repleted kidneys at the start of perfusion (285 +/- 5.1 vs. 257 +/- 5.4 mu equiv./g), by the end of the perfusion tissue K in perfused kidneys was identical in all three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of potassium concentration, type of protein supplement, and embryo density on mouse preimplantation development in vitro

Mouse preimplantation embryos were used to test the effects of three culture parameters on development of 2-cell stage embryos to the late morula stage (40 to 43 hours of culture, 65 to 80 hours after fertilization): concentration of potassium (K)--0.6 mM, 1.4 mM, and 6.0 mM; type of protein supplement, bovine serum albumin (BSA), and bovine serum immunoglobulins (BSIG); and number of embryos (2 or 20) cultured per 10- to 12-microliter drop of T6 culture medium under paraffin oil. Cell number per embryo of cultured late morulae was compared with that of same-age embryos developing in vivo. The developmental rate to late morula stage with 20 embryos per drop of medium was media containing 0.6- and 1.4-mM K, 0.15% BSA, 0.15% BSIG greater than medium containing 1.4-mM K, 0.3% BSA greater than all media containing 6.0-mM K (P less than 0.01 comparing media containing 0.6- or 1.4-mM K with media containing 6.0-mM K). For a given medium, developmental rate was significantly slower for 2 embryos per drop than for 20 embryos per drop of medium with those media containing either 0.3% BSA (for all concentrations of K tested) or 6.0-mM K (for 0.3% BSA and for 0.15% BSA + 0.15% BSIG). Finally, cell number per embryo was: in vivo-developed embryos greater than medium containing 1.4-mM K, 0.15% BSA, 0.15% BSIG much greater than 6.0- or 1.4-mM K, 0.3% BSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of potassium concentration on bicarbonate reabsorption in the rabbit proximal convoluted tubule.

The direct effects of acute changes in K+ concentration on HCO-3 (JnettCO2) and volume reabsorption (Jv) were examined in isolated perfused rabbit proximal convoluted tubules (PCT). Increasing ambient K+ concentration from 5 to 8 mM did not change JnettCO2 (94.5 +/- 16.1 vs. 98.8 +/- 17.7 pmol X mm-1 X min-1) or Jv (1.27 +/- 0.15 vs. 1.24 +/- 0.16 nl X mm-1 X min-1). In contrast, reducing ambient K+ concentration from 5 to 2 mM inhibited JnettCO2 by 22% and Jv by 29%. Reducing luminal K+ concentration from 5 to 0 mM with constant bath K+ concentration at 5 mM did not affect JnettCO2 or Jv. Further reductions in bath K+ concentration to 0.5 and 0 mM showed a similar dependence of both fluxes on K+ concentration. Half-maximum inhibition of JnettCO2 was obtained at 1.1 mM ambient K+ concentration and of Jv at 0.85 mM. At zero bath K+ concentration JnettCO2 was 6.6 +/- 2.5 pmol X mm-1 X min-1 and Jv was 0.03 +/- 0.04 nl X mm-1 X min-1. To determine whether this rate of acidification was significantly different from zero, we examined the ability of the PCT to generate tCO2 concentration gradients with zero bath K+ concentration at slow perfusion rates. The tCO2 concentration gradient generated (0.94 mM) was not different from that found when the perfusate was inserted directly into the collection pipette in the absence of a tubule (0.71 mM). These data are consistent with the view that HCO-3 reabsorption is totally dependent on the Na+-K+-ATPase pump system.

Effect of the sodium/potassium ratio on glyceraldehyde-3-phosphate dehydrogenase interaction with red cell vesicles

Binding of glyceraldehyde 3-phosphate to glyceraldehyde-3-phosphate dehydrogenase, the membrane protein known as Band 6, causes shifts in the 31P nuclear magnetic resonance spectrum of the substrate (Fossel, E.T. and Solomon, A.K. (1977) Biochim. Biophys. Acta 464, 82–92). We have studied the resonance shifts produced by varying the sodium/potassium ratio, at constant ionic strength, in order to examine the relationship between the cation transport system and glyceraldehyde-3-phosphate dehydrogenase. Alteration of the potassium concentration at the extracellular face of the vesicle affects the conformation of glyceraldehyde-3-phosphate dehydrogenase at the cytoplasmic face, thus showing that a conformation change induced by a change in extracellular potassium can be transmitted across the membrane. Alterations of the sodium concentration at the cytoplasmic face also affect the enzyme conformation, whereas sodium changes at the extracellular face are without effect. In contrast, there is no sidedness difference in the effect of potassium concentrations. The half-values for these effects are like those for activation of the red cell (Na + + K +)-ATPase. We have also produced ionic concentration gradients across the vesicle similar to those Glynn and Lew ((1970) J. Physiol. London 207, 393–402) found to be effective in running the cation pump backwards to produce adenosine triphosphate in the human red cell. The sodium/potassium concentration dependence of this process in red cells is mimicked by 31P resonance shifts in the (glyceraldehyde 3-phosphate/glyceraldehyde-3-phosphate dehydrogenase/inside out vesicle) system. These experiments provide strong support for the existence of a functional linkage between the membrane (Na + + K +)-ATPase and the glyceraldehyde-3-phosphate dehydrogenase at the cytoplasmic face.

On potassium functional feedback in neuromuscular junction

The dependence of the reversal potential (Erev) of intracellular end-plate potentials (epp) on activity patterns was studied in frog neuromuscular preparations. A shift of Erev to the positive side was found with change in frequency of stimulation from 1/sec to 50/sec. This shift corresponds to the increase of potassium concentration in the synaptic cleft to 7.0 mM. The effect of potassium concentration [K+]0 in the bath solution on quantal content (m) of epp was studied. The quantity m increased when [K+]0 was varied within the range 4.7-8.7 mM; m decreased when [K+]0 was greater than 8.7 mM. Such a relationship between m and [K+]0 is accounted for by the combined effect of potassium on transmitter secretion and electrogenic processes in motor nerve terminals. The correlation between the change of m with [K+]0 and initial epp amplitudes was found and was attributed to potassium efflux from post-synaptic region in varying quantity depending on the initial epp amplitudes. A scheme of synaptic self-regulation by means of potassium feedback is suggested.

Aldosterone Production by Isolated Glomerulosa Cells: Modulation of Sensitivity to Angiotensin II and ACTH by Extracellular Potassium Concentration.

The influence of extracellular potassium concentration on adrenal sensitivity to angiotensin II and ACTH was studied in isolated canine adrenal glomerulosa cells. When potassium was absent from the incubation medium, the aldosterone response to angiotensin II or ACTH was completely abolished. At physiologic angiotensin II concentrations (2.5 x 10(-11) M), aldosterone formation increased 4-fold when potassium concentration was increased from 2.5 to 5.0 mM, and rose 6-fold as potassium was increased from 2.5 to 7.5 mM. In the absence of angiotensin II, the same changes in potassium concentration increased aldosterone production only to 2-fold and 3.5-fold, respectively. The effect of potassium concentration upon the aldosterone response to ACTH was similar but less marked. The concentration and binding affinity of angiotensin II receptor sites in glomerulosa cells were not changed by increasing potassium concentrations from 0 to 7.5 mM. These observations demonstrate that the aldosterone response to the glomerulosa cell to angiotensin II is potassium-dependent within the physiological range for each of these stimuli. Such an interaction suggests that the in vivo effect of potassium upon aldosterone secretion includes a significant modulating action upon adrenal sensitivity to angiotensin II, as well as a direct action of potassium upon the adrenal glomerulosa cell.

Trans-synaptic regulation of tyrosine hydroxylase activity in adrenergic neurones: Effect of potassium concentration on cultured sympathetic ganglia

Superior cervical ganglia from 6-day and 4-week-old mice showed increased tyrosine hydroxylase activity when cultured for 48 h in media containing 5 or 15 times the normal potassium concentration. Increased sodium concentration had no such effect. These results suggest that depolarisation of adrenergic neurones may be important in the trans-synaptic regulation of enzyme activity in both adult and neonatal ganglia.