• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.197-210
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• 2000

Suppressive role of $Na^+-Ca^{2+}$ exchange in myocardial tension generation was examined in the negative frequency-force relationship (FFR) of electric field stimulated left atria (LA) from postnatal developing rat heart and in the whole-cell clamped adult rat ventricular myocytes with high concentration of intracellular $Ca^{2+}$ buffer (14 mM EGTA). LA twitch amplitudes, which were suppressed by cyclopiazonic acid in a postnatal age-dependent manner, elicited frequency-dependent and postnatal age-dependent enhancements after $Na^+-reduced,\;Ca^{2+}-depleted$ (26 Na-0 Ca) buffer application. These enhancements were blocked by caffeine pretreatment with postnatal age-dependent intensities. In the isolated rat ventricular myocytes, stimulation with the voltage protocol roughly mimicked action potential generated a large inward current which was partially blocked by nifedipine or $Na^+$ current inhibition. 0 Ca application suppressed the inward current by $39{\pm}4%$ while the current was further suppressed after 0 Na-0 Ca application by $53{\pm}3%.$ Caffeine increased this inward current by $44{\pm}3%$ in spite of 14 mM EGTA. Finally, the $Na^+$ current-dependent fraction of the inward current was increased in a stimulation frequency-dependent manner. From these results, it is concluded that the $Ca^{2+}$ exit-mode (forward-mode) $Na^+-Ca^{2+}$ exchange suppresses the LA tension by extruding $Ca^{2+}$ out of the cell right after its release from sarcoplasmic reticulum (SR) in a frequency-dependent manner during contraction, resulting in the negative frequency-force relationship in the rat LA.

• Membrane Journal
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• v.33 no.3
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• pp.87-93
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• 2023

Electrodialysis (ED) is essential in separating ions through an ion exchange membrane. The disposal of brine generated from seawater desalination is a primary environmental concern, and its recycling through membrane separation technology is highly efficient. Alkali is produced by several chemical industries such as leather, electroplating, dyeing, and smelting, etc. A high concentration of alkali in the waste needs treatment before releasing into the environment as it is highly corrosive and has a chemical oxygen demand (COD) value. The concentration of calcium and magnesium is almost double in brine and is the perfect candidate for carbon dioxide adsorption, a major environmental pollutant. Sodium hydroxide is essential for the metal carbonation process which, is easily produced by the bipolar membrane electrodialysis process. Various strategies are available for its recovery, like reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and ED. This review discusses the ED process by ion exchange membrane for alkali recovery are discussed.

• Applied Biological Chemistry
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• v.10
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• pp.1-13
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• 1968

Phytin is a salt(mainly calcium and magnesium) of phytic acid and its purity and molecular formula can be determined by assaying the contents of phosporus, calcium and magnesium in phytin. In order to devise a new method for the quantitative analysis of the three elements in phytin, the chelatometric method was developed as follows: 1) As the pretreatment for phytin analysis, it was ashfied st $550{\sim}600^{\circ}C$ in the presence of concentrated nitric acid. This dry process is more accurate than the wet process. 2) Phosphorus, calcium and megnesium were analyzed by the conventional and the new method described here, for the phytin sample decomposed by the dry process. The ashfied phytin solution in hydrochloric acid was partitioned into cation and anion fractions by means of a ration exchange resin. A portion of the ration fraction was adjusted to pH 7.0, followed by readjustment to pH 10 and titrated with standard EDTA solution using the BT [Eriochrome black T] indicator to obtain the combined value of calcium and magnesium. Another portion of the ration fraction was made to pH 7.0, and a small volume of standard EDTA solution was added to it. pH was adjusted to $12{\sim}13$ with 8 N KOH and it was titrate by a standard EDTA solution in the presence of N-N[2-Hydroxy-1-(2-hydroxy-4-sulfo-1-naphytate)-3-naphthoic acid] diluted powder indicator in order to obtain the calcium content. Magnesium content was calculated from the difference between the two values. From the anion fraction the magnesium ammonium phosphate precipitate was obtained. The precipitate was dissolved in hydrochloric acid, and a standard EDTA solution was added to it. The solution was adjusted to pH 7.0 and then readjusted to pH 10.0 by a buffer solution and titrated with a standard magnesium sulfate solution in the presence of BT indicator to obtain the phosphorus content. The analytical data for phosphorus, calcium and magnesium were 98.9%, 97.1% and 99.1% respectively, in reference to the theoretical values for the formula $C_6H_6O_{24}P_6Mg_4CaNa_2{\cdot}5H_2O$. Statical analysis indicated a good coincidence of the theoretical and experimental values. On the other hand, the observed values for the three elements by the conventional method were 92.4%, 86.8% and 93.8%, respectively, revealing a remarkable difference from the theoretical. 3) When sodium phytate was admixed with starch and subjected to the analysis of phosphorus, calcium and magnesium by the chelatometric method, their recovery was almost 100% 4) In order to confirm the accuracy of this method, phytic acid was reacted with calcium chloride and magnesium chloride in the molar ratio of phytic: calcium chloride: magnesium chloride=1 : 5 : 20 to obtain sodium phytate containing one calcium atom and four magnesium atoms per molecule of sodium phytate. The analytical data for phosporus, calcium and magnesium were coincident with those as determine d by the aforementioned method. The new method employing the dry process, ion exchange resin and chelatometric assay of phosphorus, calcium and magnesium is considered accurate and rapid for the determination of phytin.

• The Korean Journal of Physiology
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• v.21 no.2
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• pp.179-189
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• 1987

Since it has been known that ryanodine has a potent negative inotropic effect on the cardiac muscle contractility (Jenden and Fairhurst, 1968), ryanodine has been a subject of intensive research (Frank and Sleator, 1975; Jones et al, 1978; Sutko et al, 1985). However, the underlying mechanism for the ryanodine dependent negative inotropic effect is still uncertain. In this study, the effects of ryanodine on the generation and relaxation of contracture due to Na-withdrawal and on the force-frequency relationship of heart muscles isolated from rats and guinea pigs were measured in an effort to understand the underlying mechanism of the ryanodine-induced negative inotropy. Results are summerized as follows: 1 ) Ryanodine significantly reduced the contractility of heart muscles produced at low frequency of stimulation, but showed a little effect on the contractility at high frequency stimulation. 2) Ryanodine, at the concentrations ranging from $10^{-6}\;M$ to $10^{-8}\;M$, had no significant effect on the Na-dependent relaxation of Na-withdrawl contracture. 3) Ryandoine significantly reduced the amplitude of the Na-withdrawl contracture, and this inhibitory effect was reinforced by procaine, antiagonized by caffeine and high potassium. From these results, it may be concluded that the negative inotropic effect of ryanodine is mainly due to an inhibition of calcium release from sarcoplasmic reticulum.

• Journal of environmental and Sanitary engineering
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• v.20 no.3 s.57
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• pp.27-35
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• 2005

The ion exchange resins have been synthesized from chlormethyl styrene - 1,4 -divinyl-benzene(DVB) with $1\%,\;4\%,\;and\;10\%$-crosslinking and macrocyclic ligand of cryptand type by copolymerization method and the adsorption characteristics of uranium(VI), calcium(II) and lutetium(III) metallic ions have been investigated in various experimental conditions. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of metallic ions were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium $(UO_2^{2+})>calcium(Ca^{2+})>lutetium(Lu^{3+})$ ion. The adsorption was order of $1\%,\;4\%,\;and\;10\%$ crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Journal of Veterinary Clinics
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• v.21 no.3
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• pp.291-297
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• 2004

Aminoglycosidic antibiotics have multiple effects on muscle. For example, they have been shown to block L-type $Ca^{2+}$ channels in vascular smooth muscle, cardiac muscle and skeletal muscle. Possibly as a consequence of this effect on $Ca^{2+}$ influx, they have been shown to decrease the contractility of cardiac muscle (gentamicin). The present study evaluated the effects of gentamicin on blood pressure, vasorelaxation and left ventricular pressure. Gentamicin(10, 20, 40mg/kg) produced dose-dependent blood pressure lowering in rat. The pretreatment of MgSO$_4$ and imipramine (Na$^{+}$-Mg$^{2+}$ exchange inhibitor) had no effect in gentamicin-induced hypotension. However, the gentamicin-induced hypotension was significantly potentiated in the preincubation of verapamil or nifedipine (L-type $Ca^{2+}$ channel blockers), and was significantly attenuated by CaCl$_2$ and was slightly attenuated by caffeine (phosphodiesterase inhibitor). Gentamicin (10, 30, 100$\mu$g/m1) did not have an effect on relaxation of phenylephrine-precontracted aortic rings but high concentration of gentamicin(100, 300$\mu$g/ml) relaxed KCl-precontracted aortic rings, which relaxation was potentiated by treatment of nifedipine. Whereas gentamicin markedly decreased left ventricular developed pressure (LVDP) in perfused heart. These data suggest that gentamicin has significant blood pressure lowering of the rat, which seems to be mediated by calcium channel-sensitive pathway and blood $Ca^{2+}$ level may be important role in this response.

• KSBB Journal
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• v.8 no.4
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• pp.336-340
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• 1993

Zoogloea ramigera 115, well known type of bacteria to produce slime in sewage plants, was selected for biopolymer production. The extracted biopolymer showed high uptake capacity of metals such as cadmium and zinc. Especially the fermentor broth itself showed high adsorption of metal and could be used a biosorbent without an additional separation process. Biopolymer was immobilized into beads of calcium alginate and used in a packed bed reactor for the purpose of valued metals recovery. The biopolymer showed high removal efficiencies of 80% or greater for Cu, Cd, Mn and Zn, and high stability in sorption-desorption-resorption experiments. The immobilized biopolymer systems were found to be comparable to other metal removal systems such as ion exchange resins and to be of potential industrial application value.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.173-178
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• 1984

Correlation study was conducted to establish the optimum test level of soil improvement for good growth of corn from the relationships between the corn yield and soil chemical properties in 16 farmers' demonstration fields. Significant positive correlations between the corn yield and soil chemical properties ; pH, available phosphorus, exchangeable potassium, calcium, magnesium, cation exchange capacity. available silica, and base saturation percentage were showed but organic matter and nitrogen content were not. The proper nutrient contents in soil for expecting corn yield, 1.000kg/10a could be estimated as pH 5.6, available phosphorus 327ppm, exchangeable potassium 0.39me/100g, exchangeable calcium 5.5me/100g, exchangeable magnesium 1.3me/100g, cation exchange capacity 11.5me/100g, available silica 116ppm, base saturation percentage 58 from the relationships between the corn yield and soil chemical properties. Exchangeable aluminium were negatively correlated with not only corn yield but also pH, available phosphorus, exchangeable potassium and exchangeable calcium.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.445-456
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• 2013

In this study, desalination by electrodialysis with ion exchange membranes was applied to synthetic waters with various ion concentrations and also for ground waters from coastal areas in Korea. Electrodialysis performance on the synthetic solutions showed the similar tendency in operation time and current curves, i.e., shorter operation time and higher maximum current with increasing applied voltages. The ED results of synthetic waters with different ion compositions, i.e., $Na_2SO_4$, $MgSO_4$, $CaSO_4$, at the similar conductivity condition, i.e., $1,250{\mu}s/cm$ revealed that effects of mono- and divalent ions on water quality and performance in electrodialysis were different. The divalent ions had less efficiency in the ED compared to monovalent sodium ions and also divalent calcium ions showed better performance than Mg ions. The electrodialysis on the ground waters produced high quality of drinking water. The groundwater from SungRoe however showed a buildup of membrane resistance. Organic matter concentrations and great portions of divalent ions in the groundwater were possible causes of the deteriorated performance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.108-115
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• 2002

The effects of long-term fertilization on soil properties and nutrient availability are not well documented for cassava cultivation in Vietnam. In 1990, a field research plots were established with 12 treatments to test the effect of different rates of nitrogen (N), phosphorus (P) and potassium (K) on soil properties in Acrisols at Thai Nguyen University in Northern Vietnam. In 1999, composite soil samples (0 to 20cm depth) were collected from eight selected plots for measurements of nutrient supply rates by ion exchange membrane probes and for growing corn and canola in a growth chamber with and without added lime. Generally, long-term nitrogen (N) fertilization increased available N supply rates but decreased available potassium (K) and magnesium (Mg). Long-term phosphorus(P) applications increased canola N, calcium (Ca) and Mg uptake. Canola P uptake increased with increased P rates only when lime was added. Long-term K applications increased canola N, K, Ca, Mg uptake but only significantly increased corn N uptake. Liming significantly increased uptake of N, P, K, Ca, Mg and S for both corn and canola. However, N $H_{4-}$N, K and Mg soil supply rates were reduced when lime was added, due to competition between Ca from the added lime and other nutrients.