• International Journal of Oral Biology
• /
• 제43권1호
• /
• pp.43-51
• /
• 2018

$K^+$ channels are key components of the primary and secondary basolateral $Cl^-$ pump systems, which are important for secretion from the salivary glands. Paroxetine is a selective serotonin reuptake inhibitor (SSRI) for psychiatric disorders that can induce QT prolongation, which may lead to torsades de pointes. We studied the effects of paroxetine on a human $K^+$ channel, human ether-a-go-go-related gene (hERG), expressed in Xenopus oocytes and on action potential in guinea pig ventricular myocytes. The hERG encodes the pore-forming subunits of the rapidly-activating delayed rectifier $K^+$ channel ($I_{Kr}$) in the heart. Mutations in hERG reduce $I_{Kr}$ and cause type 2 long QT syndrome (LQT2), a disorder that predisposes individuals to life-threatening arrhythmias. Paroxetine induced concentration-dependent decreases in the current amplitude at the end of the voltage steps and hERG tail currents. The inhibition was concentration-dependent and time-dependent, but voltage-independent during each voltage pulse. In guinea pig ventricular myocytes held at $36^{\circ}C$, treatment with $0.4{\mu}M$ paroxetine for 5 min decreased the action potential duration at 90% of repolarization ($APD_{90}$) by 4.3%. Our results suggest that paroxetine is a blocker of the hERG channels, providing a molecular mechanism for the arrhythmogenic side effects of clinical administration of paroxetine.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
• /
• pp.232-235
• /
• 2006

Using 30 days of hourly visible channel data and DIScrete Ordinate Radiative Transfer (DISORT) model (6S), Aerosol optical depth (AOD) at $0.55{\mu}m$ was retrieved over the East Asia. In contrast with the AOD retrieval using low-earth-orbit satellites such as MODIS (Moderate-Res olution Spectroradiometer) or MISR (Multiangle Imaging SpectroRadiometer), this algorithm with geostationary satellite can improve the monitoring of AOD without the limitation of temporal resolution. Due to the limited number of channels in the conventional meteorological imager onboard the geostationary satellite, an AOD retrieval algorithm utilizing a single visible channel has been introduced. This single channel algorithm has larger retrieval error of AOD than other multiple-channel algorithm due to errors in surface reflectance and atmospheric property. In this study, the effects of manifold atmospheric and surface properties on the retrieval of AOD from the geostationary satellite, are investigated and compared with the AODs from AERONET and MODIS. To improve the accuracy of retrieved AOD, efforts were put together to minimize uncertainties through extensive sensitivity tests. This algorithm can be utilized to retrieve aerosol information from previous geostationary satellite for long-term climate studies.

• 센서학회지
• /
• 제25권5호
• /
• pp.344-348
• /
• 2016

We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.

• 생명과학회지
• /
• 제27권11호
• /
• pp.1349-1356
• /
• 2017

$K^+$ 통로 개방제들은 심근, 뇌, 골격근 등에서 세포막 혹은 미토콘드리아 내막에 존재하는 큰 전도성의 $Ca^{2+}$-의 존성 $K^+$ (BK) 통로 및 ATP-조절성 $K^+$ 통로(ATP-sensitive $K^+$ channels, $K_{ATP}$)에 작용하여 허혈성 혹은 산화성 세포 손상을 완화하는 효과가 있는 것으로 보고되어 있다. 본 연구에서는 망막 색소 상피세포주인 ARPE-19 세포를 실험 모델로 하여 큰 전도성의 BK 통로 개방제인 NS 1619가 유사한 보호 효과를 나타낼 수 있는지, 또한 그 작용기전이 무엇인지를 확인하고자 하였다. AREE-19 세포를 여러 형태의 산화 스트레스에 노출시켜 세포 손상을 유발하고 그 손상의 정도 및 이에 미치는 NS 1619의 효과를 trypan blue 배출능, Tunel 염색 분석을 통하여 측정하였다. NS 1619는 여러 형태의 산화 스트레스에 의한 괴사성 및 apoptosis에 의한 세포 손상을 효과적으로 방지하였으며 그 보호 효과는 BK 통로 봉쇄제인 paxilline 의해 차단되었다. NS 1619는 $H_2O_2$에 의한 세포내 ATP 고갈을 현저히 완화시켰으며, 또한 MTT 환원능으로 측정한 미토콘드리아의 기능을 보호하는 효과를 보였다. 유세포형광 분석법을 이용한 실험에서 NS 1619는 $H_2O_2$에 의한 미토콘드리아 막전압의 소실을 유의하게 방지하였다. 이상의 결과들을 종합하면 NS 1619는 망막 색소 상피세포에서 산화성 세포 손상을 방지하는 효과를 나타내며 그 기전에 미토콘드리아 기능에 대한 보호 작용이 연관되어 있는 것으로 사료된다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제25권3호
• /
• pp.227-237
• /
• 2021

Carbon monoxide (CO) is a cardioprotectant and potential cardiovascular therapeutic agent. Human cardiac fibroblasts (HCFs) are important determinants of myocardial structure and function. Large-conductance Ca2+-activated K+ (BK) channel is a potential therapeutic target for cardiovascular disease. We investigated whether CO modulates BK channels and the signaling pathways in HCFs using whole-cell mode patch-clamp recordings. CO-releasing molecules (CORMs; CORM-2 and CORM-3) significantly increased the amplitudes of BK currents (IBK). The CO-induced stimulating effects on IBK were blocked by pre-treatment with specific nitric oxide synthase (NOS) blockers (L-NG-monomethyl arginine citrate and L-NG-nitroarginine methyl ester). 8-bromo-cyclic GMP increased IBK. KT5823 (inhibits PKG) or ODQ (inhibits soluble guanylate cyclase) blocked the CO-stimulating effect on IBK. Moreover, 8-bromo-cyclic AMP also increased IBK, and pre-treatment with KT5720 (inhibits PKA) or SQ22536 (inhibits adenylate cyclase) blocked the CO effect. Pre-treatment with N-ethylmaleimide (a thiol-alkylating reagent) also blocked the CO effect on IBK, and DL-dithiothreitol (a reducing agent) reversed the CO effect. These data suggest that CO activates IBK through NO via the NOS and through the PKG, PKA, and S-nitrosylation pathways.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권12호
• /
• pp.4584-4599
• /
• 2021

In IEEE 802.11p-based wireless access in vehicular environments (WAVE) communication systems, channel estimation (CE) is one of the important issues to provide stable communication service. It is hard to apply conventional CE schemes based on data pilot to real systems, because error propagation occurs in high mobility and modulation order environments, resulting in degrading the CE performance. In this paper, we propose one data pilot using multiple receive antennas (ODPM) CE scheme based on the weighted sum using update matrix (WSUM) with time-domain averaging (TDA) to overcome this problem. Within the process of WSUM-TDA in the proposed scheme, the maximum ratio combining (MRC) technique is applied so as to create more accurate one data pilot. Moreover, a new reliability test criterion is proposed as the fashion of utilizing MRC, which makes it possible to apply selective TDA that guarantees performance improvement. In simulation results, the packet error rate (PER) performance of the proposed ODPM is compared with that of conventional CE methods and its superiority is demonstrated.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
• /
• pp.183-183
• /
• 2008

This paper presents the time responses of calcium ($Ca^{2+}$) ion concentration of MG-63 cells induced by a constant shear stress in micro channel were observed in the real time. Most of cells have similar rising time. There were some time delays because of the initial position of the cell in the micro channel along the pressure-driven fluid flow. The concentration of $Ca^{2+}$ exponentially decreased while time constant of each profile did not have any relation to the peak value of concentration.

• 한국생물물리학회:학술대회논문집
• /
• 한국생물물리학회 2002년도 제9회 학술 발표회 프로그램과 논문초록
• /
• pp.32-32
• /
• 2002

To understand the functional roles of the neuron-specific $\beta$-subunit of large-conductance calcium-activated potassium ($BK_{Ca}$) channel, we isolate the full-length complementary DNA of $\beta$4-subunit from rat brain library and investigated its effects on the function of $\alpha$-subunit (Slo). The deduced amino acid sequence of rat $\beta$4 (r$\beta$4), 210 amino acids in length, was closely related to those of $\beta$4 subunits in other mammalian species but showed only a limited sequence homology to the other $\beta$-subunits, $\beta$1 to $\beta$3.(omitted)d)

• 한국생물물리학회:학술대회논문집
• /
• 한국생물물리학회 1999년도 학술발표회 진행표 및 논문초록
• /
• pp.56-56
• /
• 1999

Change of membrane property can affect the activity of membrane proteins. In this work, we investigated the single channel properties of large conductance $Ca^{2+}$-activated $K^{+}$(BK) channels in planar lipid bilayers of different thickness. First, we recorded the activity of single BK channels from rat skeletal muscle incorporated into the control bilayer, then increased the bilayer thickness by perfusing the recording solution with the one saturated with n-pentane, or reduced the thickness by adding diheptanoylphosphatidylcholine (di$C_{7:0}$PC) to the recording soluton.(omitted)

• The Korean Journal of Physiology and Pharmacology
• /
• 제13권3호
• /
• pp.241-249
• /
• 2009

Although extracellular $Ca^{2+}$ entry through the voltage-dependent $Ca^{2+}$ channels plays an important role in the spontaneous phasic contractions of the pregnant rat myometrium, the role of the T-type $Ca^{2+}$ channels has yet to be fully identified. The aim of this study was to investigate the role of the T-type $Ca^{2+}$ channel in the spontaneous phasic contractions of the rat myometrium. Spontaneous phasic contractions and $[Ca^{2+}]_i$ were measured simultaneously in the longitudinal strips of female Sprague-Dawley rats late in their pregnancy (on day 18 ${\sim}$ 20 of gestation: term=22 days). The expression of T-type $Ca^{2+}$ channel mRNAs or protein levels was measured. Cumulative addition of low concentrations (< 1 ${\mu}M$) of nifedipine, a L-type $Ca^{2+}$ channel blocker, produced a decrease in the amplitude of the spontaneous $Ca^{2+}$ transients and contractions with no significant change in frequency. The mRNAs and proteins encoding two subunits (${\alpha}$ 1G, ${\alpha}$ 1H) of the T-type $Ca^{2+}$ channels were expressed in longitudinal muscle layer of rat myometrium. Cumulative addition of mibefradil, NNC 55-0396 or nickel induced a concentration-dependent inhibition of the amplitude and frequency of the spontaneous $Ca^{2+}$ transients and contractions. Mibefradil, NNC 55-0396 or nickel also attenuated the slope of rising phase of spontaneous $Ca^{2+}$ transients consistent with the reduction of the frequency. It is concluded that T-type $Ca^{2+}$ channels are expressed in the pregnant rat myometrium and may play a key role for the regulation of the frequency of spontaneous phasic contractions.