• The Korean Journal of Physiology and Pharmacology
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• 제15권5호
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• pp.285-289
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• 2011

Shilajit, a medicine herb commonly used in Ayurveda, has been reported to contain at least 85 minerals in ionic form that act on a variety of chemical, biological, and physical stressors. The substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis (Vc) are involved in orofacial nociceptive processing. Shilajit has been reported to be an injury and muscular pain reliever but there have been few functional studies of the effect of Shilajit on the SG neurons of the Vc. Therefore, whole cell and gramicidin-perfotrated patch clamp studies were performed to examine the action mechanism of Shilajit on the SG neurons of Vc from mouse brainstem slices. In the whole cell patch clamp mode, Shilajit induced short-lived and repeatable inward currents under the condition of a high chloride pipette solution on all the SG neurons tested. The Shilajit-induced inward currents were concentration dependent and maintained in the presence of tetrodotoxin (TTX), a voltage gated $Na^+$ channel blocker, CNQX, a non-NMDA glutamate receptor antagonist, and AP5, an NMDA receptor antagonist. The Shilajit-induced responses were partially suppressed by picrotoxin, a $GABA_A$ receptor antagonist, and totally blocked in the presence of strychnine, a glycine receptor antagonist, however not affected by mecamylamine hydrochloride (MCH), a nicotinic acetylcholine receptor antagonist. Under the potassium gluconate pipette solution at holding potential 0 mV, Shilajit induced repeatable outward current. These results show that Shilajit has inhibitory effects on the SG neurons of Vc through chloride ion channels by activation of the glycine receptor and $GABA_A$ receptor, indicating that Shilajit contains sedating ingredients for the central nervous system. These results also suggest that Shilajit may be a potential target for modulating orofacial pain processing.

• 한국전기전자재료학회논문지
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• 제33권6호
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• pp.454-459
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• 2020

In this study, a TiO₂/TiO_2-x-based resistance variable memory was fabricated using a DC/RF magnetron sputtering system and ALD. In order to analyze the effect of oxygen plasma treatment on the performance of resistance random access memory (ReRAM), the TiO₂/TiO_2-x-based ReRAM was evaluated by applying RF power to the TiO_2-x oxygen-holding layer at 30, 60, 90, 120, and 150 W, respectively. The ReRAM was fabricated, and the electrical and surface area performances were compared and analyzed. In the case of ReRAM without oxygen plasma treatment, the I-V curve had a hysteresis curve shape, but the width was very small, with a relatively high surface roughness of the oxygen-retaining layer. However, in the case of oxygen plasma treatment, the HRS/LRS ratio for the I-V curve improved as the applied RF power increased; stable improvement was also noted in the surface roughness of the oxygen-retaining layer. It was confirmed that the low voltage drive was not smooth due to charge trapping in the oxygen diffusion barrier layer owing to the high intensity ReRAM applied with an RF power of approximately 150 W.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.93-94
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• 2007

An essential step for SERGI is to show the TRANSFORMER PROTECTOR (TP) efficacy for all transformers and all types of rupture of insulation. Its research program philosophy is thus to maintain a strong connection between experiments and the theoretical developments. Up to now, two TP test campaigns have been performed, both under the worst conditions by creating low impedance faults leading to electrical arcs inside the transformer tank dielectric oil. In 2002, Electricite de France performed 28 TP tests. Then, in 2004, a second campaign of 34 TP tests was carried out by CEPEL, the Brazilian independent High Voltage Laboratory. For the 62 tests, each transformer was equipped with the TP, which reacts directly to the moving dynamic pressure peak, shock wave, caused by the low impedance fault. When an electrical arc occurs, only one pressure peak is generated. The initial energy transfer is almost instantaneous, and so is the phase change. Because of the oil inertia, the gas is very quickly pressurised. As it is more difficult to vaporise a liquid than to crack oil-vapour into smaller molecules, the arc location would mainly remain in the gaseous phase after and less gas will be produced. As a result, when comparing tests for which pressure peaks are respectively equal to 8 bar (116 psi) and 8.8 bar (127 psi), the corresponding arc energies vary by an order 10 of magnitude (0.1 MJ and 1 MJ respectively). The correlation of the results obtained between arc energy and dynamic pressure demonstrates that the arc energy is not the key parameter during transformer tank explosion, which is in opposition with the common electrical engineers belief.

• Biomolecules & Therapeutics
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• 제31권2호
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• pp.168-175
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• 2023

Tramadol is an opioid analog used to treat chronic and acute pain. Intradermal injections of tramadol at hundreds of millimoles have been shown to produce a local anesthetic effect. We used the whole-cell patch-clamp technique in this study to investigate whether tramadol blocks the sodium current in HEK293 cells, which stably express the pain threshold sodium channel Na_v1.7 or the cardiac sodium channel Na_v1.5. The half-maximal inhibitory concentration of tramadol was 0.73 mM for Na_v1.7 and 0.43 mM for Na_v1.5 at a holding potential of -100 mV. The blocking effects of tramadol were completely reversible. Tramadol shifted the steady-state inactivation curves of Na_v1.7 and Na_v1.5 toward hyperpolarization. Tramadol also slowed the recovery rate from the inactivation of Na_v1.7 and Na_v1.5 and induced stronger use-dependent inhibition. Because the mean plasma concentration of tramadol upon oral administration is lower than its mean blocking concentration of sodium channels in this study, it is unlikely that tramadol in plasma will have an analgesic effect by blocking Na_v1.7 or show cardiotoxicity by blocking Na_v1.5. However, tramadol could act as a local anesthetic when used at a concentration of several hundred millimoles by intradermal injection and as an antiarrhythmic when injected intravenously at a similar dose, as does lidocaine.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.673-681
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• 2023

Hydrocarbon-based polymer membranes to replace perfluorinated polymer membranes are being continuously researched. However, hydrocarbon-based membranes have a problem in that they are less durable than fluorine-based membranes. In this study, we sought to compare the annealing effect to improve the durability of sulfonated poly(ether ether ketone) (SPEEK). After membranes formation, thermogravimetric analysis and tensile strength were measured to compare changes in membranes properties due to annealing. After manufacturing the membrane and electrode assembly (MEA), the initial performance and chemical durability was compared with unit cell operation. During the 24-hour annealing process, the strength increased due to the increase in-S-O-S-crosslinking, and the sulfonic acid group decreased, leading to a decrease in I-V performance. By annealing, the hydrogen permeability was reduced to less than 1/10 of that of the nafion membrane, and as a result, open circuit voltage (OCV) and durability was improved. The SPEEK membranes annealed for 24 hours showed higher durability than the nafion 211 membranes of the same thickness.

• The Korean Journal of Physiology and Pharmacology
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• 제2권6호
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• pp.733-742
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• 1998

Background: We have previously reported that not only cGMP but also 8-Br-cGMP or 8-pCPT-cGMP, specific and potent stimulators of cGMP-dependent protein kinase (cGMP-PK), increased basal L-type calcium current $(I_{Ca})$ in rabbit ventricular myocytes. Our findings in rabbit ventricular myocytes were entirely different from the earlier findings in different species, suggesting that the activation of cGMP-PK is involved in the facilitation of $I_{Ca}}$ by cGMP. However, there is no direct evidence that cGMP-PK can stimulate $I_{Ca}}$ in rabbit ventricular myocytes. In this report, we focused on the direct effect of cGMP-PK on $I_{Ca}}$ in rabbit ventricular myocytes. Methods and Results: We isolated single ventricular myocytes of rabbit hearts by using enzymatic dissociation. Regulation of $I_{Ca}}$ by cGMP-PK was investigated in rabbit ventricular myocytes using whole-cell voltage clamp method. $I_{Ca}}$ was elicited by a depolarizing pulse to +10 mV from a holding potential of -40 mV. Extracellular 8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphate (8-pCPT-cGMP), potent stimulator of cGMP-dependent protein kinase (cGMP-PK), increased basal $I_{Ca}}$. cGMP-PK also increased basal $I_{Ca}}$. The stimulation of basal $I_{Ca}}$ by cGMP-PK required both 8-Br-cGMP in low concentration and intracellular ATP to be present. The stimulation of basal $I_{Ca}}$ by cGMP-PK was blocked by heat inactivation of the cGMP-PK and by bath application of 8-(4-chlorophenylthio)-guanosine-3',5'-cyclic monophosphate, Rp-isomer (Rp-pCPT-cGMP), a phosphodiesterase-resistant cGMP-PK inhibitor. When $I_{Ca}}$ was increased by internal application of cGMP-PK, IBMX resulted in an additional stimulation of $I_{Ca}}$. In the presence of cGMP-PK, already increased $I_{Ca}}$ was potentiated by bath application of isoprenaline or forskolin or intracellular application of cAMP. Conclusions: We present evidence that cGMP-PK stimulated basal $I_{Ca}}$ by a direct phosphorylation of L-type calcium channel or associated regulatory protein in rabbit ventricular myocytes.

• The Korean Journal of Physiology
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• 제26권2호
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• pp.113-122
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• 1992

It is well known that chromaffin cells of adrenal medulla secrete catecholamine in response to sympathetic nerve activation and the influx of $Ca^{2+}$ through the voltage dependent $Ca^{2+}$ channels (VDCC) in the cell membrane do a major role in this secretory process. In this study, we explored the effect of divalent cations on VDCC of rat chromaffin cells. Rat (Sprague-Dawley rat, 150-250 gm) chromaffin cells were isolated and cultured. Standard giga seal, whole cell recording techniques were employed to study $Ca^{2+}$ current with external and internal solutions that could effectively isolate VDCC currents $(NMG\;in\;external\;and\;TEA\;and\;Cs^{2+}\;in\;internal\;solution)$. The voltage dependence and the inactivation time course of VDCC in our cells were identical to those of bovine chromaffin cells. A persistent inward current was first activated by depolarizing step pulse from the holding potential (H.P.) of -80 mV to -40 mV, increased to maximum amplitude at around +10 mV, and became smaller with progressively higher depolarizing pulses to reverse at around +60 mV. The inactivation time constant $(\tau)$, fitted from the long duration test potential (2 sec) was $1295.2{\pm}126.8$ msec $(n=20,\;1\;day\;of\;culture,\;mean\;{\pm}S.E.M.)$ and the kinetic parameters were not altered along the culture duration. Nicardipine $(10\;{\mu}M)$ blocked the current almost completely. Among treated divalent cations such as $Cd^{2+},\;Co^{2+},\;Ni^{2+},\;Zn^{2+}\;and\;,Mn^{2+},\;Cd^{2+}$ was the most potent blocker on VDCC. When the depolarizing step pulse from -80 mV to 10 mV was applied, the equilibrium dissociation constant $(K_d)$ of $Cd^{2+}\;was\;39\;{\mu}M,\;K_d\;of\;Co^{2+}\;was\;100\;{\mu}M\;and\;K_d\;of\;Ni^{2+}];was];780{\mu}M.$ The principal findings of this study are as follows. First, the majority of $Ca^{2+}$ channels in rat chromaffin cells are well classified to L-type $Ca^{2+}$ channel in the view of kinetics and pharmacology. Second, all divalent cations tested could block the $Ca^{2+}$ current and the most potent blocker among the tested was $Cd^{2+}$.

• Molecules and Cells
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• 제20권2호
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• pp.235-240
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• 2005

Extracts of pine needles (Pinus densiflora Sieb. et Zucc.) have diverse physiological and pharmacological actions. In this study we show that pine needle extract alters pacemaker currents in interstitial cells of Cajal (ICC) by modulating ATP-sensitive $K^+$ channels and that this effect is mediated by prostaglandins. In whole cell patches at $30^{\circ}C$, ICC generated spontaneous pacemaker potentials in the current clamp mode (I = 0), and inward currents (pacemaker currents) in the voltage clamp mode at a holding potential of -70 mV. Pine needle extract hyperpolarized the membrane potential, and in voltage clamp mode decreased both the frequency and amplitude of the pacemaker currents, and increased the resting currents in the outward direction. It also inhibited the pacemaker currents in a dose-dependent manner. Because the effects of pine needle extract on pacemaker currents were the same as those of pinacidil (an ATP-sensitive $K^+$ channel opener) we tested the effect of glibenclamide (an ATP-sensitive $K^+$ channels blocker) on ICC exposed to pine needle extract. The effects of pine needle extract on pacemaker currents were blocked by glibenclamide. To see whether production of prostaglandins (PGs) is involved in the inhibitory effect of pine needle extract on pacemaker currents, we tested the effects of naproxen, a non-selective cyclooxygenase (COX-1 and COX-2) inhibitor, and AH6809, a prostaglandin EP1 and EP2 receptor antagonist. Naproxen and AH6809 blocked the inhibitory effects of pine needle extract on ICC. These results indicate that pine needle extract inhibits the pacemaker currents of ICC by activating ATP-sensitive $K^+$ channels via the production of PGs.

• Applied Biological Chemistry
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• 제47권4호
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• pp.390-395
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• 2004

토마토 뿌리에 존재하는 이온채널의 특성을 조사하기 위하여, 마이크로솜을 분리하고 전기생리용 분석장치가 연결된 인공지질 이중막에 유입하였다. 그 결과 다섯 종류의 이온채널을 확인하였고, 이들 중 450 pS의 전기전도도를 갖는 비선택성 양이온채널을 가장 자주 관측하였다. 이 채널은 세 가지의 subconductance 상태를 보였으며, 이들의 전기전도도는 450, 257, 105 pS으로 측정되었다. 모든 subconductance 상태는 막전위 변화에 따른 전류변화가 직선적으로 나타났다. 채널의 활성은 양의 막전위에서 열림과 닫힘이 반복되는 전이상태를 보였지만, 음의 막전위에서는 평균 열림시간과 함께 열림확률도 증가하였다. 막전위 -40mV에서 측정한 채널의 열림확률은 0.83이었다. 이온선택성을 측정하기 위하여 지질막의 한쪽에만 50mM의 $K^+$ 또는 $Na^+$을 가하여 비대칭 이온조건을 만들었을 때, 두 경우 모두에서 전류역전전위는 동일하게 약 -l0mV 이동하였다. 이것은 450 pS채널이 $K^+$과 $Na^+$을 구별없이 통과시킴을 나타낸다. 중금속 이온들 중, $100\;{\mu}M$ 농도의 $La^{3+}$과 $Ba^{2+},\;Zn^{2+}$는 채널의 활성을 크게 저해하여 열림확률을 0.2 이하로 감소시켰다. 그러나, $Al^{3+}$과 $Cd^{2+}$은 활성을 약 20% 저해하였다. 흥미롭게도, 각각의 중금속 이온은 서로 다른 형태로 채널활성을 저해하였다. $La^{3+}$은 $500\;{\mu}M$ 농도에서 모든 subconductance 상태를 저해하였으나, $Zn^{2+}$는 1 mM의 농도에서도 105 pS의 subconductance 상태는 저해하지 않았다. 또한 $Cd^{2+}$은 음의 막전위에서도 채널의 열림을 long-opening상태에서 전이상태 열림으로 전환시켰다. 이러한 결과는 중금속 이온들이 채널단백질에 각각의 결합부위를 가질 수 있을 가능성을 의미하여, 식물 뿌리의 생리현상에서 450 pS 채널의 기능적 역할 뿐 만아니라 구조적 특징을 탐색할 수 있는 유용한 조절자나 탐색자로 이용될수 있음을 시사한다.

• 대한치과교정학회지
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• 제32권3호
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• pp.227-234
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• 2002

본 연구는 조골세포의 특성을 가지고 있는 G292세포주를 이용하여 세포막 이온통로에 대한phorbol ester의 효과를 조사하여 protein kinase C (PCK)의 이온통로에 대한 작용기전을 밝히고자 하였다. Patch clamp 기법을 이용하여 G292 세포에서 cell-attached configuration으로 단일이온통로의 활동을 관찰하고 Phorbol 12, 13-dibutyrate (PDBu)의 효과를 관찰하였다. 안정상태 G292 세포에서 cell-attached 모드로 세포막의 단일이 온통로 활동을 관찰한 결과 45pS의 $K^+$통로가 특징 적으로 우세하였다. 유리 전극 내부에 세포내 액과 세포외 액을 사용하여 전류-전압의 관계를 조사한 결과, 세포내 액을 사용하는 경우에는 역전전압이 5.5mV이었으며 세포외액을 사용하는 경우에는 -27mV이었다. PDBu는 45pS의 이온통로를 10nM이상의 농도에서 이온통로의 열릴 확률을 증가시켰으며 PKC억제제인 staurosporine 10nM에 의하여 차단되는 특성을 보였다. PDBu는 45pS의 이온통로에 작용하여 전류-전압의 관계에서 역전전압을 음의 방향으로 이동시켰으며 동일한 막전압에서 단일이온통로의 전류 크기를 증가시켰다. G292세포에서 PDBu에 의하여 PKC가 활성화되는 것을 western blot으로 확인한 결과 PDBu 0.luM은 세포질에서 세포막으로 PKC translocation을 유의하게 증가시키는 것을 확인하였다. 이상의 결과는 G292세포에서 phorbol ester의 일종인 PDBu가 세포내 PKC를 활성화시켜 45pS의 이온통로를 활성화시키며 이러한 작용의 결과로 세포막전압의 변화가 세포의 기능을 조절할 것으로 사료된다.