• Natural Product Sciences
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• 제19권4호
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• pp.290-296
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• 2013

In preliminary tests, we examined the effect of several fractions isolated from fermented pine needle extract on pacemaker potentials in cultured interstitial cells of Cajal (ICCs) from the mouse colon using a whole cell patch clamp technique. Among these fractions, Fraction 3 (F3) elicited the most powerful depolarization of membrane. Therefore, the aim of the present study was to investigate the effect of F3 obtained from fermented extract of Pinus densiflora needle on pacemaker potentials in ICCs and to establish its mechanism of action. Colonic ICCs generated spontaneous periodic pacemaker potentials in the current-clamp mode. F3 depolarized the membrane and decreased the frequency and amplitude of pacemaker potentials in a dose-dependent fashion. The F3-induced effects on pacemaker potentials were blocked by methoctramine, a muscarinic $M_2$ receptor antagonist, and by glycopyrrolate, a muscarinic $M_3$ receptor antagonist. The F3-induced effects on pacemaker potentials were blocked by external $Na^+$-free solution and by flufenamic acid, a non-selective cation channel blocker, as well as by the removal of external $Ca^{2+}$ and in the presence of thapsigargin, a $Ca^{2+}$-ATPase inhibitor in the endoplasmic reticulum. Taken together, these results suggest that F3 of pine needle extract modulates the pacemaker activity of colonic ICCs by the activation of non-selective cation channels via muscarinic $M_2$ and $M_3$ receptors. And external $Ca^{2+}$ influx and intracellular $Ca^{2+}$ release are involved in F3 actions on ICCs.

• The Korean Journal of Physiology and Pharmacology
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• 제14권5호
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• pp.305-310
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• 2010

The human $ether$-$a$-$go$-$go$-related gene ($hERG$) channel is important for repolarization in human myocardium and is a common target for drugs that prolong the QT interval. We studied the effects of two antipsychotics, tiapride and sulpiride, on hERG channels expressed in $Xenopus$ oocytes and also on delayed rectifier $K^+$ currents in guinea pig cardiomyocytes. Neither the amplitude of the hERG outward currents measured at the end of the voltage pulse, nor the amplitude of hERG tail currents, showed any concentration-dependent changes with either tiapride or sulpiride ($3{\sim}300{\mu}M$). However, our findings did show that tiapride increased the potential for half-maximal activation ($V_{1/2}$) of HERG at $10{\sim}300{\mu}M$, whereas sulpiride increased the maximum conductance ($G_{max}$) at 3, 10 and $100{\mu}M$. In guinea pig ventricular myocytes, bath applications of 100 and $500{\mu}M$ tiapride at $36^{\circ}C$ blocked rapidly activating delayed rectifier $K^+$ current ($I_{Kr}$) by 40.3% and 70.0%, respectively. Also, sulpiride at 100 and $500{\mu}M$ blocked $I_{Kr}$ by 38.9% and 76.5%, respectively. However, neither tiapride nor sulpiride significantly affected the slowly activating delayed rectifier $K^+$ current ($I_{Ks}$) at the same concentrations. Our findings suggest that the concentrations of the antipsychotics required to evoke a 50% inhibition of IKr are well above the reported therapeutic plasma concentrations of free and total compound.

• 동의생리병리학회지
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• 제19권3호
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• pp.743-748
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• 2005

This study was performed for the investigation of vasodilatory efficacy and its underlying mechanisms of Jagumhuan(JGH), a herbal remedy. JGH produced completely endothelium-dependent relaxation and relaxed phenylephrine(PE)-precontracted aorta in a concentration dependent manner. The magnitude of relaxation was greater in PE induced contraction than that of KCl, suggesting involvement of $K^+$ channel in the relaxant effect. Both glibenclamide$(10^{-5}M)$, a $K_{ATP}$ channel inhibitor and indometacin, a cyclooxygenase inhibitor, completely prevented this relaxation. The relaxation effects of JGH, involve in part the release of nitric oxide from the endothelium as pretreatment with L-NAME, an NOS inhibitor, and methylene blue, a cGMP inhibitor, attenuated the responses by 62% and 58%, respectively. In addition, nitrite was produced by JGH in human aortic smooth muscle cells and human umbilical vein endothelial cells. The relaxant effect of JGH was also inhibited by 55.41% by tetraethylammonium(TEA; 5mM), a $K_{Ca}$ channel inhibitor. In the absence of extracellular $Ca^{2+}$, pre-incubation of the aortic rings with JGH significantly reduced the contraction by PE, suggesting that the relaxant action of the JGH includes inhibition of $Ca^{2+}$ release from intracellular stores. These results indicate that in rat thoracic aorta, JGH may induce vasodilation through ATP sensitive $K^+$ channel activation by prostacyclin production. However, the relaxant effect of JGH may also mediated in part by NO pathways and $Ca^{2+}$ activated $K^+$ channel.

• 비파괴검사학회지
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• 제25권1호
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• pp.20-26
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• 2005

유도초음파는 판, 봉 또는 관과 같은 구조물의 장거리 탐상에 사용되고 있다. 그러나, 유도초음파에는 그 모드가 많고 전파속도가 달라서, 원하는 모드를 선택적으로 발생시키고 수신하는 기법이 유도초음파를 응용하는데 핵심적인 기술 중 하나이다. 본 연구에서는 배열형 탐촉자의 위상을 조절하여 유도초음파를 발생시키는 방법에 대하여 연구하였다. 이를 위하여 8채널 초음파 펄서/리시버, 그리고 각각의 채널을 일정한 시간간격으로 구동할 수 있는 회로를 개발하였다. 8개의 탐촉자를 만들어서 배열형으로 사용하여 유도 초음파를 발생시켰다. 이웃한 요소 탐촉자 사이의 구동시간 간격을 제어하여 이에 맞는 위상속도를 지닌 유도초음파를 선택적으로 발생시켰고, 발생된 유도초음파의 군속도를 측정하였으며, 배열탐촉자에서 수신된 신호를 시간지연을 가지고 합성하여 유도초음파의 모드를 선택적으로 수신하였다. 그 결과, 이웃한 요소 탐촉자 사이의 구동시간 간격을 바꿈으로서 원하는 모드의 유도초음파를 선택적으로 발생시킬 수 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.101-101
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• 2018

Quantitative measurement of chloride ion concentration has an important role in various fields of electrochemistry, medical science, biology, metallurgy, architecture, etc. Among them, its importance of architecture is ever-growing due to unexpected degradations of building structure. These situations are caused by corrosion of reinforced concrete (RC) structure of buildings. And chloride ions are the most powerful factors of RC structure corrosion. Therefore, precise inspection of chloride ion concentration must be required to increase the accuracy of durability monitoring. Multi-walled Carbon nanotubes (MWCNTs) have high chemical resistivity, large surface area and superior electrical property. Thus, it is suitable for the channels of electrical signals made by the sensor. Silver nanoparticles were added to giving the sensing property. CuBTC, one of the metal organic frameworks (MOFs), was employed as a material to improve the sensing property because of its hydrophilicity and high surface area to volume ratio. In this study, sensing element was synthesized by various chemical reaction procedures. At first, MWCNTs were functionalized with a mixture of sulfuric acid and nitric acid because of enhancement of solubility in solution and surface activation. And functionalized MWCNTs, silver nanoparticles, and CuBTC were synthesized on PTFE membrane, one by one. Electroless deposition process was performed to deposit the silver nanoparticles. CuBTC was produced by room temperature synthesis. Surface morphology and composition analysis were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), respectively. X-ray photoelectron spectroscopy (XPS) was also performed to confirm the existence of sensing materials. The electrical properties of sensor were measured by semiconductor analyzer. The chloride ion sensing characteristics were confirmed with the variation of the resistance at 1 V.

• Animal cells and systems
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• 제12권3호
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• pp.137-141
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• 2008

Molecular cloning revealed the three isoforms($Ca_v3.1,\;Ca_v3.2,\;and\;Ca_v3.3$) of the T-type calcium channel subfamily. Expression studies exhibited their distinctive electrophysiological and pharmacological properties, accounting for diverse properties of T-type calcium channel currents previously characterized from isolated cells. However, electrophysiological properties of ion channels have shown to be more diversified by their splice variants. We here searched splice variants of rat $Ca_v3.1$ T-type channel by reverse-transcription-polymerase chain reaction(RT-PCR) to further explore diversity of $Ca_v3.1$. Interestingly, analyses of cloned RT-PCR products displayed that there were at least four splicing variants of rat $Ca_v3.1$ in the loop connecting repeats III and IV. Southern blot analyses indicated that the predominantly detected variant in brain was $Ca_v3.1a$(492 bp), which were rarely detected in most of peripheral tissues. Other two variants($Ca_v3.1c$, 546 bp; $Ca_v3.1d$, 525 bp) were detected in most of the tissues examined. The smallest isoform($Ca_v3.1b$, 471 bp) was rarely detected all the tissues. Electrophysiological characterization of the splicing variants indicated that the splice variants differ in inactivation kinetics and the voltage dependence of activation and inactivation as well.

• 약학회지
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• 제55권3호
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• pp.247-250
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• 2011

An increase in ventricular pressure can alter cardiac excitation and contraction. Recent report has demonstrated that fluid pressure (FP) suppresses L-type $Ca^{2+}$ current with acceleration of the current inactivation in ventricular myocytes. Since the L-type $Ca^{2+}$ channels known to be regulated by intracellular pH ($pH_i$), this study was designed to explore whether pressurized fluid flow affects pHi in isolated rat ventricular myocytes. A flow of pressurized (~16 dyne/$cm^2$) fluid, identical to that bathing the myocytes, was applied onto single myocytes, and intracellular $H^+$ concentration was monitored using confocal $H^+$ imaging. FP significantly decreased $pH_i$ by $0.07{\pm}0.01$ pH units (n=16, P<0.01). Intracellular acidosis enhances the activity of $Na^+-H^+$ exchanger (NHE). Therefore, we examined if the NHE activity is increased by FP using the NHE inhibitor, HOE642. Although HOE642 did not alter $pH_i$ in control conditions, it decreased $pH_i$ in cells pre-exposed to FP, suggesting enhancement of NHE activity by FP. In addition, FP-induced intracellular acidosis was larger in cells pre-treated with HOE642 than in cells under the control conditions. These results suggest that FP induces intracellular acidosis and that NHE may contribute to extrude $H^+$ during the FP-induced acidosis in rat ventricular myocytes.

• The Korean Journal of Physiology and Pharmacology
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• 제3권3호
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• pp.329-337
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• 1999

Thyroid hormone-induced cellular dysfunctions may be associated with changes in the intracellular $Ca^{2+}$ concentration. The ryanodine receptor, a $Ca^{2+}$ release channel of the SR, is responsible for the rapid release of $Ca^{2+}$ that activates cardiac muscle contraction. In the excitation-contaction coupling cascade, activation of ryanodine receptors is initiated by the activity of sarcolemmal $Ca^{2+}$ channels, the dihydropyridine receptors. In hyperthyroidism left ventricular contractility and relaxation velocity were increased, whereas these parameters were decreased in hypothyroidism. The mechanisms for these changes have been suggested to include alterations in the expression and/or activity levels of various proteins. In the present study, quantitative changes of ryanodine receptors and the dihydropyridine receptors, and the functional consequences of these changes in various thyroid states were investigated. In hyperthyroid hearts, $[^3H]ryanodine$ binding and ryanodine receptor mRNA levels were increased, but protein levels of ryanodine were not changed significantly. However, the above parameters were markedly decreased in hypothyroid hearts. In case of dihydropyridine receptor, there were a significant increase in the mRNA and protein levels, and [3H]nitrendipine binding, whereas no changes were observed in these parameters of hypothyroid hearts. Our findings indicate that hyperthyroidism is associated with increases in ryanodine receptor and dihydropyridine receptor expression levels, which is well correlated with the ryanodine and dihydropyridine binding. Whereas opposite changes occur in ryanodine receptor of the hypothyroid hearts.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권2호
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• pp.109-114
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• 2005

Ion fluxes across the plasma membrane activated by 1 mM $Ce^{4+}$, cell apoptosis and taxol biosynthesis in suspension cultures of Taxus cusp/data were studied. The extracellular pH sharply decreased upon the addition of 1 mM $Ce^{4+}$, then increased gradually and exceeded the initial pH value over a time period of 12 h. The extracellular $Ca^{2+}$ concentration decreased within the first 3 h after the addition of $Ce^{4+}$, then gradually decreased to one third of initial value in control at about 72 h and remained unchanged afterwards. Experiments with an ion channel blocker and a $Ca^{2+}$-channel blocker indicated that the dynamic changes in extracellular pH and the $Ca^{2+}$ concentration resulted from the $Ce^{4+}$-induced activation of W uptake and $Ca^{2+}$ influx across the plasma membrane via ion channels. A pretreatment of the ion channel blocker initiated $Ce^{4+}$-treated cells to undergo necrosis, and the prior addition of the $Ca^{2+}$-channel blocker inhibited $Ce^{4+}$-induced taxol biosynthesis and apoptosis. It is thus inferred that W uptake is necessary for cells to survive a $Ce^{4+}$-caused acidic environment and is one of the mechanisms of $Ce^{4+}$-induced apoptosis. Furthermore, the $Ca^{2+}$ influx across the plasma membrane mediated both the $Ce^{4+}$-induced apoptosis and taxol biosynthesis.

• 한국전자파학회논문지
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• 제23권8호
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• pp.909-922
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• 2012

유한한 전파자원을 효과적으로 활용하기 위해서는 전파자원을 활용한 유망 비즈니스 모델을 발굴, 평가하고, 이에 기반하여 구체적인 기술 개발 계획과 산업 활성화 정책을 수립하는 것이 필요하다. 본 연구는 미래 전파 활용 유망 분야를 탐색하여 성공 가능성이 높은 유망 비즈니스 모델을 설계하고, 제시된 비즈니스 모델의 사업화 타당성을 평가하며, 비즈니스 모델의 활성화를 위한 정책을 논의하는 것을 목표로 한다. 지역 또는 시간적으로 사용되지 않는 TV 채널인 TV 유휴 대역을 대상으로 분석하였으며, 이는 최근 지상파 TV 방송의 디지털 전환에 따라 핵심적인 전파자원으로 부각되고 있다. 연구 결과, 방송형과 통신형을 비롯한 네 가지 비즈니스 모델이 도출되었으며, 각 비즈니스 모델을 고객 가치, 이익 공식, 핵심 자원, 핵심 프로세스 등 4가지 관점에서 고찰하고, 기술성, 사업성, 수용성 측면에서 사업화 타당성을 평가하였다. 또한, TV 유휴 대역을 활용한 비즈니스 모델의 활성화를 위한 정부 및 사회 구성원의 과제를 논의하였다.