• The Korean Journal of Physiology and Pharmacology
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• 제9권1호
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• pp.37-43
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• 2005

Our previous report demonstrated that chick myoblasts are equipped with $Ca^{2+}$-permeable stretchactivated channels and $Ca^{2+}-activated$ potassium channels ($K_{Ca}$), and that hyperpolarization-induced by $K_{Ca}$ channels provides driving force for $Ca^{2+}$ influx through the stretch-activated channels into the cells. Here, we showed that acetylcholine (ACh) also hyperpolarized the membrane of cultured chick myoblasts, suggesting that nicotinic acetylcholine receptor (nAChR) may be another pathway for $Ca^{2+}$ influx. Under cell-attatched patch configuration, ACh increased the open probability of $K_{Ca}$ channels from 0.007 to 0.055 only when extracellular $Ca^{2+}$ was present. Nicotine, a nAChR agonist, increased the open probability of $K_{Ca}$ channels from 0.008 to 0.023, whereas muscarine failed to do so. Since the activity of $K_{Ca}$ channel is sensitive to intracellular $Ca^{2+}$ level, nAChR seems to be capable of inducing $Ca^{2+}$ influx. Using the $Ca^{2+}$ imaging analysis, we were able to provide direct evidence that ACh induced $Ca^{2+}$ influx from extracellular solution, which was dramatically increased by valinomycin-mediated hyperpolarization. In addition, ACh hyperpolarized the membrane potential from $-12.5{\pm}3$ to $-31.2{\pm}5$ mV by generating the outward current through $K_{Ca}$ channels. These results suggest that activation of nAChR increases $Ca^{2+}$ influx, which activates $K_{Ca}$ channels, thereby hyperpolarizing the membrane potential in chick myoblasts.

• Asian-Australasian Journal of Animal Sciences
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• 제25권4호
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• pp.552-558
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• 2012

A $2{\times}2$ factorial experiment was conducted to study the effect of dietary calcium and non-phytate phosphorus (nPP) imbalance on calbindin and NaPi-IIb mRNA levels in the small intestine and tibia parameters of broiler chicks. One hundred and forty four 1-d-old Arbor Acres male broiler chicks were divided into four treatments consisted of six replicates with six chicks each. The two dietary calcium levels were 1.10% and 0.60%, and two dietary nPP levels were 0.50% and 0.27%. Results showed that a high Ca/nPP ratio diet (4.07:1) significantly depressed feed intake and weight gain of broilers (p<0.05), but a lower Ca:nPP ratio (1.2:1) had no influence (p>0.05). Low-Ca with low-P diet resulted in low tibia minerals and tibia breaking strength of broilers, and all the tibia parameters were further decreased when the dietary ratio of Ca to P was relative higher. Low dietary Ca or P up-regulated the calbindin and NaPi-IIb mRNA expression levels. Low Ca with normal P diet up-regulated duodenal calbindin mRNA expression level to the greatest extent. Low P with a normal Ca diet significantly enhanced NaPi-IIb mRNA expression level to the highest extent. These results suggest that the calbindin and NaPi-IIb mRNA expression were enhanced by the imbalance between dietary Ca and nPP, and their expression were not only influenced by Ca or nPP level, but also the ratio of Ca:nPP.

• Molecules and Cells
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• 제23권1호
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• pp.11-16
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• 2007

N,N-dimethyl-D-erythro-sphingosine (DMS) is an N-methyl derivative of sphingosine and an inhibitor of protein kinase C (PKC) and sphingosine kinase (SK). In the present study, we examined the effects of DMS on intracellular $Ca^{2+}$ concentration, pH, and glutamate uptake in human 1321N1 astrocytes. DMS increased intracellular $Ca^{2+}$ concentration and cytosolic pH in a concentration-dependent manner. Pretreatment of the cells with the $G_{i/o}$ protein inhibitor PTX and the PLC inhibitor U73122 had no obvious effect. However, removal of extracellular $Ca^{2+}$ with the $Ca^{2+}$ chelator EGTA or depletion of intracellular $Ca^{2+}$ stores with thapsigargin impeded the DMS-induced increase of intracellular $Ca^{2+}$ concentration. Pretreatment of cells with $NH_4Cl$ or monensin reduced the DMS-induced $Ca^{2+}$ increase. However, inhibition of the DMS-induced $Ca^{2+}$ increase with BAPTA did not influence the DMS-induced pH increase. DMS also inhibited glutamate uptake by the 1321N1 astrocytes in a concentration-dependent manner. It also increased intracellular $Ca^{2+}$ and pH in PC12 neuronal cells. Our observations on the effects of DMS on 1321N1 astrocytes and PC12 neuronal cells point to a physiological role of DMS in the brain.

• Journal of the Korean Magnetics Society
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• 제13권3호
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• pp.121-126
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• 2003

The electromagnetic properties and microstructures of the basic composition of (N $i_{0.2}$C $u_{0.2}$Z $n_{0.6}$)$_{1.085}$(F $e_2$ $O_3$)$_{0.915}$ were invested by changing of the additive Sn $O_2$, CaO amounts and ferrite processes. There is no variation of grain size by changing additive amount. It can reduce the total loss when (N $i_{0.2}$C $u_{0.2}$Z $n_{0.6}$)$_{1.085}$(F $e_2$ $O_3$)$_{0.915}$ composition sintered at 1150 $^{\circ}C$ better than 130$0^{\circ}C$. Additive CaO confirmed of useful addition for the reduce total loss, because it increasing sintering density. Decreasing total loss were observed by adding both Sn $O_2$ 0.06 wt％ and CaO 0.4 wt％.

• Horticultural Science & Technology
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• 제34권6호
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• pp.871-877
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• 2016

Recycling nutrient solutions in closed hydroponic production systems is usually accompanied by an imbalance of nutrient solutions when concentration is controlled according to electrical conductivity (EC) levels. This study investigated whether it was possible to automatically control the concentrations of five essential elements nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) using only N, K and Ca ion sensors. N, P, K, Ca, and Mg uptake was measured in the nutrient solution, and relationships between absorbed ions were analyzed through twice-repeated experiments in lettuce. Results confirmed that the pattern of $PO_4$ ion uptake was similar that of N, and the pattern of Mg ion uptake was similar that of Ca. $PO_4$ ion uptake was most highly correlated with N, and Mg was most highly correlated with Ca. Regression coefficients of N and $PO_4$ were significantly different at 1.04 and 0.55, respectively, but were similar between Ca and Mg at 0.35 and 0.40, respectively. Additional experiments were conducted to measure nutrient uptake in pak choi and rose plants, both to confirm the results from the first experiment in lettuce, and to assess possible application to other crops. Coefficients of determination both for N and $PO_4$, and Ca and Mg were considerably high ($R^2=0.86$) in cultured pak choi, and similar results were observed in cultured rose ($R^2=0.87$ and 0.73, respectively). Regression coefficients for cultured pak choi were 0.56 and 0.24, respectively, and for rose were 0.51 and 0.16, respectively. Although the results obtained for N and $PO_4$ were not consistent between the lettuce experiments, N and $PO_4$ have similar regression coefficients for all crops. No common coefficient was found between Ca and Mg.

• The Korean Journal of Physiology and Pharmacology
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• 제8권5호
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• pp.265-272
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• 2004

The present study was attempted to investigate the effect of cilnidipine (FRC-8635), which is a newly synthesised novel dihydropyridine (DHP) type of organic $Ca^{2+}$ channel blockers, on secretion of catecholamines (CA) evoked by acetylcholine (ACh), high $K^+$, DMPP and McN-A-343 from the isolated perfused rat adrenal gland. Cilnidipine $(1{\sim}10{\mu}M)$ perfused into an adrenal vein for 60 min produced relatively dose- and time-dependent inhibition in CA secretory responses evoked by ACh $(5.32{\times}10^{-3}M),\;DMPP\;(10^{-4}M\;for\;2\;min)$ and McN-A-343 $(10^{-4}M\;for\;2\;min)$. However, lower dose of cilnidipine did not affect CA secretion by high $K^+\;(5.6{\times}10^{-2}\;M)$, higher dose of it reduced greatly CA secretion of high $K^{+}$. Cilnidipine itself did fail to affect basal catecholamine output. In the presence of cilnidipine $(10{\mu}M)$, the CA secretory responses evoked by Bay-K-8644 $(10{\mu}M)$, an activator of L-type $Ca^{2+}$ channels and cyclopiazonic acid $(10{\mu}M)$, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase were also inhibited. Moreover, ${\omega}-conotoxin\;GVIA\;(1{\mu}M)$, a selective blocker of the N-type $Ca^{2+}$ channels, given into the adrenal gland for 60 min, also inhibited time-dependently CA secretory responses evoked by Ach, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid. Taken together, these results demostrate that cilnidipine inhibits CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors from the isolated perfused rat adrenal gland without affecting the basal release. However, at lower dose, cilnidipine did not affect CA release by membrane depolarization while at larger dose inhibited that. It seems likely that this inhibitory effect of cilnidipine is exerted by blocking both L- and N-type voltage-dependent $Ca^{2+}$ channels (VDCCs) on the rat adrenomedullary chromaffin cells, which is relevant to inhibition of both the $Ca^{2+}$ influx into the adrenal chromaffin cells and intracellular $Ca^{2+}$ release from the cytoplasmic store. It is thought that N-type VDCCs may play an important role in regulation of CA release from the rat adrenal medulla.

• Korean Chemical Engineering Research
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• 제40권6호
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• pp.746-751
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• 2002

Fluidized bed combustion is a coal combustion technology that can reduce both SOx and NOx emission; SOx is removed by limestone that is fed into the combustion chamber and the NOx is reduced by low temperature combustion in a fluidized bed combustor and air stepping, but $N_2O$ generation is quite high. $N_2O$ is not only a greenhouse gas but also an agent of ozone destruction in the stratosphere. The calcium oxide(CaO) is known to be a catalyst of $N_2O$ decomposition. This study of $N_2O$ decomposition reaction in fixed bed reactor packed over CaO bed has been conducted. Effects of parameters such as concentration of inlet $N_2O$ gas, reaction temperature, CaO bed height and effect of $CO_2$, NO, $O_2$ gas on the decomposition reaction have been investigated. As a result of the experiment, it has been shown that $N_2O$ decomposition reaction increased with the increasing fixed bed temperature. While conversion of the reaction was decreased with increasing $CO_2$ concentration. Also, under the present of NO, the conversion of $N_2O$ decomposition is decreased. From the result of kinetic study gained the heterogeneous reaction rate on $N_2O$ decomposition. In the case of $N_2O$ decomposition over CaO, heterogeneous reaction rate is. $\frac{d[N_2O]}{dt}=\frac{3.86{\times}10^9{\exp}(-15841/R)K_{N_2O}[N_2O]}{(1+K_{N_2O}[N_2O]+K_{CO_2}[CO_2])}$. In this study, it is found that the calcium oxide is a good catalyst of $N_2O$ decomposition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제16권11호
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• pp.1029-1034
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• 2003

The Bi$_2$Sr$_2$Ca$_{n}$Cu$_{n+1}$ O$_{x}$, superconducting thin films arc fabricated by using the sputtering and evaporation method. Because we confirmed the sticking ratio of Bi element in the Bi$_2$Sr$_2$Ca$_{n}$Cu$_{n+1}$ O$_{x}$ superconducting thin film fabricated by using the sputtering method was much lower than the expected value, to get the enough number of the flakes of Bi, faraday cup was used to evaporate Bi clement. As a result of the fabrication, Bi 2201 and Bi 2212 single phases could be made by the optima of deposition condition. And we confirmed the sticking coefficient of Bi element was clearly related to the temperature change of the substrate and the generation of Bi22l2 phase

• The Korean Journal of Physiology and Pharmacology
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• 제3권3호
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• pp.357-364
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• 1999

We investigated the role of $Ca^{2+}$ and protein kinases/phosphatases in the stimulatory effect of insulin on glucose transport. In isolated rat adipocytes, the simple omission of $CaCl_2$ from the incubation medium significantly reduced, but did not abolish, insulin-stimulated 2-deoxy glucose (2-DG) uptake. Pre-loading adipocytes with intracellular $Ca^{2+}$ chelator, 5,5'-dimethyl bis (o-aminophenoxy)ethane-N,N,N'N' tetraacetic acetoxymethyl ester (5,5'-dimethyl BAPTA/AM) completely blocked the stimulation. Insulin raised intracellular $Ca^{2+}$ concentration $([Ca^{2+}]_i)$ about 1.7 times the basal level of $72{\pm}5$ nM, and 5,5'-dimethyl BAPTA/AM kept it constant at the basal level. This correlation between insulin-induced increases in 2-DG uptake and $[Ca^{2+}]_i$ indicates that the elevation of $[Ca^{2+}]_i$ may be prerequisite for the stimulation of glucose transport. Studies with inhibitors (ML-9, KN-62, cyclosporin A) of $Ca^{2+}-calmodulin$ dependent protein kinases/phosphatases also indicate an involvement of intracellular $Ca^{2+}.$ Additional studies with okadaic acid and calyculin A, protein phosphatase-1 (PP-1) and 2A (PP-2A) inhibitors, indicate an involvement of PP-1 in insulin action on 2-DG uptake. These results indicate an involvement of $Ca^{2+}-dependent$ signaling pathway in insulin action on glucose transport.

• Animal cells and systems
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• 제1권1호
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• pp.123-128
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• 1997

The characteristics of allelic polymorphisms of the two (CA)n microsatellite (p599 and ㅅ599) markers spanning the long arm of chromosome 5 were studied in 52 DNA samples from unrelated inhabitants of Seoul (Korea) by using the polymerase chain reaction (PCR) to investigate differences in allele frequencies between Korean and Caucasian populations. The 6 alleles were observed for p599 (CA)n with a polymorphism informative content (PIC) value of 0.71 and 9 alleles for ㅅ599 (CA)n with a PIC value of 0.82. The observed heterozygote frequencies of the loci were estimated to 0.730 and 0.846, respectively. Several allele frequencies of two loci showed significant differences between Korean and Caucasian populations. Genotype data from the two loci were consistent with the Hardy-Weinberg equilibrium by x2 test. Linkage disequilibrium between p599 (CA)n and ㅅ599 (CA)n loci was observed in x2 test between the observed and expected frequency of allelic association. The probability of matching calculated at each locus was 0.104 for p599 (CA)n and 0.043 for ㅅ599 (CA)n, respectively. These results demonstrate the need to determine populationspecific allele frequency distributions for polymorphic markers when performing genetic linkage studies in racially defined several populations.