• 공업화학
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• 제23권5호
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• pp.474-479
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• 2012

막결합 축전식 탈염(MCDI) 기술을 이용하여 $Na^{+}$와 $Ca^{2+}$ 이온이 혼합된 용액에서 $Ca^{2+}$ 이온의 선택적 제거 가능성을 연구하였다. 양이온교환막인 CMX막에 대한 $Ca^{2+}$ 이온의 선택성을 확인하기 위해 흡착평형 실험을 실시하였다. 그리고 MCDI 셀을 이용해 혼합용액(5 meq/L NaCl + 2 meq/L $CaCl_{2}$)에 대한 탈염실험을 수행하였다. 흡착평형 실험결과 용액과 CMX막에서 $Ca^{2+}$ 이온의 당량분율은 각각 28.6, 87.2%를 보여 CMX막이 $Ca^{2+}$ 이온에 대해 높은 선택성을 갖는 것을 확인하였다. MCDI 셀에 일정한 전류를 인가하면서 셀 전위가 1.0 V에 도달할 때까지 탈염실험을 실시하였다. 그 결과 흡착된 이온의 총량은 인가한 전류밀도에 큰 영향을 받지 않고 일정하였다. 그러나 흡착된 이온 중 $Ca^{2+}$ 이온의 비율은 전류밀도에 반비례하였으며 200, 300, 500, $700\;A/m^{2}$의 전류밀도에서 각각 81.4, 78.4, 77.0, 74.5%로 나타났다. 이러한 결과는 낮은 전류밀도에서 CMX막에 흡착된 $Ca^{2+}$ 이온의 비율이 높았기 때문인 것으로 판단된다.

• The Korean Journal of Physiology and Pharmacology
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• 제11권5호
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• pp.183-188
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• 2007

Using BHK cells with stable expression of cardiac $Na^+/Ca^{2+}$ exchanger(BHK-NCX1), reverse mode(i.e. $Ca^{2+}$ influx mode) of NCX1 current was recorded by whole-cell patch clamp. Repeated stimulation of reverse NCX1 produced a cytosolic $Ca^{2+}$-dependent long-term inactivation of the exchanger activity. The degrees of inactivation correlated with NCX1 densities of the cells and were attenuated by reduced $Ca^{2+}$ influx via the reverse exchanger. The inactivation of NCX1 was attenuated by(i) inhibition of $Ca^{2+}$ influx with reduced extracellular $Ca^{2+}$, (ii) treatment with NCX1 blocker($Na^{2+}$), and (iii) increase of cytoplasmic $Ca^{2+}$ buffer(EGTA). In BHK-NCX1 cells transiently expressing TRPV1 channels, $Ca^{2+}$ influx elicited by capsaicin produced a marked inactivation of NCX1. We suggest that cytoplasmic $Ca^{2+}$ has a dual effect on NCX1 activities, and that allosteric $Ca^{2+}$ activation of NCX1 can be opposed by the $Ca^{2+}$-dependent long-term inactivation in intact cells.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2002년도 제9회 학술 발표회 프로그램과 논문초록
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• pp.37-37
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• 2002

The Na$^{＋}$-Ca$^{2＋}$ exchanger (NCX) is known to playa critical role in the regulation of intracellular $Ca^{2＋}$ in many tissues and cells. Three isoforms have been cloned (NCXl, NCX2, NCX3). Among the isoforms, NCX2 and NCX3 are expressed at high levels in brain and in a few other tissues. But the differential properties of the isoforms are not yet clearly established.(omitted)

• 폴리머
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• 제37권4호
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• pp.533-538
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• 2013

염화나트륨은 우리 몸의 체액에 존재하며, 혈액 속에 약 0.9 wt%의 농도로 존재하여 삼투압을 유지하는 중요한 역할을 하고 있다. 그러나 사람들이 섭취하는 소금의 양은 증가하는 추세이며, 과량 섭취로 인해 고혈압 등의 원인이 되기도 한다. 본 연구에서는 생체적합성 이온성 고분자들의 특정 반대이온을 칼슘과 칼륨으로 치환시켜 나트륨 이온과의 이온교환을 통해 고분자에 나트륨이 흡착되어 대변으로 배출시킬 수 있는지를 in vitro 실험과 in vivo 실험을 통해 연구하였다. 조사된 고분자들 중 칼슘과 칼륨의 폴리스티렌설폰산, 칼슘 치환된 카라기난과 타마린드가 우수한 나트륨 치환 능력을 보유하고 있음을 확인하였고, 체온과 인공위액 및 인공장액의 조건에서도 나트륨 치환능을 유지하는 것을 확인하였다. 이러한 고분자들의 난용성 특징을 통해 구강 내에서는 맛의 변화를 주지 않으면서 나트륨을 흡착해 배설하는 메카니즘을 나트륨 과다 섭취에 따른 문제 해결을 위해 활용할 수 있을 것으로 사료된다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.37-37
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• 2003

We have shown the $Ca^{2+}$-activated chloride current is present in cardiac myocyte in rabbit pulmonary vein (Kim et al., 2002). This current amplitude was increased as [N $a^{+}$]$_{i}$ was increased and we suggested this chloride current may be involve in the spontaneous action potential frequency change. Since this current is activated by the increase of intracellular $Ca^{2+}$, we would like to test what is the inducer of the increase of [C $a^{2+}$]$_{i}$ between a L-type $Ca^{2+}$-current or a reverse mode of N $a^{+}$-C $a^{2+}$ exchange current. White rabbit (1.5 kg) was used and anesthetized with Ketamin (100 mg/kg). Pulmonary vein (PV) was isolated and sleeve area between left atrium and PV was dissected. Using collagenase (Worthington 0.7 mg/cc), single cardiac myocytes were isolated. In the presence of 15 mM of N $a^{＋}$, three steps of voltage pulses were applied (holding potential : -40 ㎷, -80 ㎷ for 50 msec, 30 ㎷ for 5 msec, 10 ㎷ steps from -70 ㎷ to 60 ㎷). The inward and outward tail current was activated after brief 5 msec prepulse. The outward tail current was blocked by the removal of extracellular chloride substituted by glucuronic acid or by a chloride channel blocker, 5 mM 9-AC. But the inward tail current was still remained even though the amplitude was decreased. The reversal potentials were changed to the direction of the change of chloride equilibrium potential ( $E_{Cl}$ ) but the shift of equilibrium potential was not enough to match to the theoretical equilibrium potential shift. In the presence of L-type $Ca^{2+}$ channel blocker, nifedipine 1 uM, inward tail currents were greatly reduced but the outward current tail currents were still remained. In the presence of N $a^{+}$-C $a^{2+}$ exchange current blocker, 10 uM KB-R7943, the inward and outward tail currents were blocked almost completely. We tried to test the $Ca^{2+}$sensitivity of the chloride current with various [C $a^{2+}$]$_{i}$ in pipette solution from 100 nM to 1 uM but we failed to activate $Ca^{2＋}$-activated chloride currents even though the cell became contracted in the presence of 1 uM $Ca^{2+}$. From these results, we could conclude that the increase of [C $a^{2+}$]$_{i}$ to activate the outward $Ca^{2+}$-activated chloride current was mainly induced by the activation of the reverse mode of N $a^{+}$-C $a^{2+}$ exchanger, But for the increase of [C $a^{2+}$]$_{i}$ to activate the inward tail current, L-type $Ca^{2+}$ current may be the major provoking current. Since the cytosolic increase of [C $a^{2+}$]$_{i}$ through pipette solution have failed to activate $Ca^{2+}$-activated chloride current, this chloride current may have very low $Ca^{2+}$ sensitivity or a comparmental increase $Ca^{2+}$ such as in subsarcolemmal space may activate the chloride current. Since there are several reports and models that the increase of $Ca^{2+}$ in subsarcolemmal space would be over several to tens of uM, both possibility may be valid together.uM, both possibility may be valid together.

• The Korean Journal of Physiology
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• 제23권2호
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• pp.301-312
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• 1989

It well known that the magnitude of contraction and the shape of action potential depend upon the stimulation frequency and the duration of resting period (positive and negative staircase). Although the underlying mechanism of the staircase phenomenon is not fully understood, it has been suggested that staircase could be related to the intracllular $Ca^{2+}$ concentration. In order to elucidate the role of intracellular $Ca^{2+}$ on the contraction and action potential staircases, we examined the effects of 1 mM 4-aminopyridine (4-AP), 0.5 uM verapamil, 1 uM ryanodine, or reduction of extracellular Na concentration to 30% $(substituted\;by\;equimolar\;Li^+)$ in small atrial strips of the rabbit $(3{\times}10\;mm)$. The results obitained were as follows; 1) When the stimulation frequency was increased from 0.1 Hz to 2 Hz, positive staircase of the contraction and elevation of plateau level in action potential were found in control and the conditions of Na reduction and treatments of 4-AP, verapamil and ryanodine. 2) When stimulation frequency returned to 0.1 Hz from 1 min rest just after 2 Hz stimulation fer 1 min, the magnitudes of initial few contractions were larger than that of steady state contraction (post-rest potentiation) except, ryanodine or Na-reduction groups. 3) Negative staircase of contraction was developed in control and 4-AP group at post-rest 0.1 Hz stimulation and the plateau level of the action potential was decreased at the same time. But the reduction of contraction or the plateau level was much smaller in 4-AP group and than in control. From the above results it can be concluded that contraction and action potential staircase is dependent upon transmembrane $Ca^{2+}-current\;and\;Ca^{2+}$release from the SR.

• The Korean Journal of Physiology and Pharmacology
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• 제12권5호
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• pp.267-274
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• 2008

Since first discovered in chick skeletal muscles, stretch-activated channels (SACs) have been proposed as a probable mechano-transducer of the mechanical stimulus at the cellular level. Channel properties have been studied in both the single-channel and the whole-cell level. There is growing evidence to indicate that major stretch-induced changes in electrical activity are mediated by activation of these channels. We aimed to investigate the mechanism of stretch-induced automaticity by exploiting a recent mathematical model of rat atrial myocytes which had been established to reproduce cellular activities such as the action potential, $Ca^{2+}$ transients, and contractile force. The incorporation of SACs into the mathematical model, based on experimental results, successfully reproduced the repetitive firing of spontaneous action potentials by stretch. The induced automaticity was composed of two phases. The early phase was driven by increased background conductance of voltage-gated $Na^+$ channel, whereas the later phase was driven by the reverse-mode operation of $Na^+/Ca^{2+}$ exchange current secondary to the accumulation of $Na^+$ and $Ca^{2+}$ through SACs. These results of simulation successfully demonstrate how the SACs can induce automaticity in a single atrial myocyte which may act as a focus to initiate and maintain atrial fibrillation in concert with other arrhythmogenic changes in the heart.

• 상하수도학회지
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• 제27권4호
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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.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.175-175
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• 1996

The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is Processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region and sites and cellular mechanisms of their actions have been a target of numerous studies. In this study, single neurons were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by the patch clamp method. Young rats (7-14 days) were anesthetized with diethyl-ether, and the lumbar spinal cord was excised and cut transversely at a thickness of 30$\mu\textrm{m}$ by Vibroslicer. The treatment of spinal slices with low concentration of proteases (pronase and thermolysin 0.75 mg/$m\ell$) and mechanical dissociation yielded isolated neurons with near intact morphology. Multipolar, ellipsoidal and bipolar, and pyramidal cells were shown. By applying step voltage pulses to neurons held at -70 mV, two types of inward currents and one outward currents observed. The fast activating and inactivating inward current was the Na$\^$+/ current because of its fast kinetics and blocking by 0.5${\mu}$M TTX, a specific blocker of Na$\^$+/ channel. The second type of inward currents were sustained. Based on their kinetics and current-voltage relations, it was likely that the second type of inward current was the voltage-dependent Ca$\^$2+/ current. In the presence of TTX, the steady-state currents mainly represented outward K$\^$+/ current which looked like the delayed rectifier K$\^$+/ current. In addition, the membrane currents produced by agonist of excitatory amino acid (EAA) receptor and the endogenous transmitter candidate L-glutamate were recorded in isolated whole-cell voltage clamped neurons as well as responses to inhibitory amino acids (${\gamma}$-amino butyric acid, glycine). Drugs were applied by a method that allows complete exchange of the solution within 1 sec; an infinite number of solutions can be applied to a single cell.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.810-815
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• 2011

역삼투막을 이용한 해수담수화 과정에서 발생하는 농축수 내에는 고농도의 $Na^+$ 이온이 포함되어 있으며, 이를 경제성 있는 NaOH 용액으로 회수하기 위해 전기분해를 적용하였다. 실험실 규모의 전기분해장치를 구성하여 실험조건의 변화에 따른 NaOH 용액의 합성농도를 비교하였다. 이온교환막의 종류(CIMS 막, Nafion 막), 이온교환막의 전처리 유무, 농축수의 유입 유속(73 mL/min ~ 200 mL/min), 모의 농축수의 농도(1.5 M ~ 5 M), 전류(1.5 A, 2 A) 등의 인자를 변화시켜 전기분해를 수행한 결과, CIMS 막은 Nafion 막에 비하여 NaOH 용액의 합성효율은 뛰어나지만, 장시간운전 이후에 염소가스에 대한 내구성이 떨어졌다. 또한, 모의 농축수의 $Na^+$ 이온농도와 전류가 높을수록 NaOH 용액의 합성효율은 증가하였으나, 모의 농축수의 유입 유속이 낮을수록 합성효율은 증가하였다.