• The Korean Journal of Physiology
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• v.28 no.1
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• pp.51-59
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• 1994

This study was carried out to elucidate the excitatory mechanisms of Substance P in the antral circular muscle, using isometric contraction recording, conventional microelectrode method and whole-cell patch clamp technique. Substance P produced tonic and phasic contractions in a dose-dependent manner and depolarized membrane potential with increased amplitude of slow waves in muscle strips. Voltage-dependent $Ca^{2+}$ currents were increased by the application of Substance P from a holding potential of -60mV to 50mV in 10mV steps and this effect was blocked by the addition of an antagonist. Also Substance P increased transient and spontaneous oscillatory $K^+$ outward currents. The enhanced outward currents were abolished by apamin in dispersed single cells. These results suggest that the depolarization of membrane potential by Substance P activates voltage-dependent $Ca^{2+}$ channels, which represents an excitatory response in the antral circular muscle and led to an increase in $Ca^{2+}\;activated\;K^+\;currents$.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.3
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• pp.262-269
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• 2000

말초 미각계 및 중추 미각계에서 산화질소의 역할과 그것의 합성효소의 존재는 아직 규명되지 않고 있다. 본 연구는 말초미각계인혀와 미각구심성신경 그리고 중추미각계인 뇌간고속핵에서 산화질소 합성효소의 분포 및 면역조직화학 방법과 고삭신경의 extracellular recording 뇌간고속핵 절편 whole cell patch 방법으로 조사하였다. 신경성 산화질소 합성효소는 혀의 전방에 위치한 심상유두와 유곽유두에 약하게 존재하였으며 미뢰주위와 결체조직에 존재하는 신경섬유 및 혀의 상피층에 풍부하게 존재하였다. 혀에 소금물을 가하여 증가된 고삭신경의 복합전위는 산화질소 유리제인 SNP에 의해 증가되었으며 내인성 산화질소 합성효소 억제제인 L-NAME와 soluble guanylate cyclase 억제제인 ODQ에 의해 억제되었다. 문측 연수에 존재한 문측 고속핵과 진전핵에서 nNOS가 풍부하게 존재하였다. 문측 고속핵의 신경들은 안정막전위가 $-48{\pm}52mV$였고 활동전위의 크기는 $74{\pm}11mV$였다. SNP에 의해 뇌간 고속핵 신경들이 탈분극되었으며 current clamp하였을 때 활동전압의 빈도가 증가하였다. 또한 SNP에 의한 문측 고속핵의 탈분극과 활동전압 빈도증가는 L-NAME와 ODQ에 의해 감소되었다. 이상의 실험결과는 산화질소 합성효소가 혀와 뇌간고속핵에 존재하며 여기서 유리된 내인성 산화질소가 말초성 및 중추성 미각기전에 관여하리라 사료된다.

• Biomolecules & Therapeutics
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• v.14 no.2
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• pp.102-105
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• 2006

We examined the effects of psoralen derivatives on a rapidly activating delayed rectifier $K^+$ channel (hKv1.5) cloned from human heart and stably expressed in $Ltk^-$ cells. Using the whole cell configuration of the patch-clamp technique, we found that the five psoralen derivatives inhibited hKv1.5 current. Especially, 4-(2-Propenyloxy)-7H-furo[3,2-g][1]benzopyran-7-one (compound 5) was more potent than the inhibition of the hKv1.5 current of psoralen. The compound 5 inhibited the hKv1.5 current in a concentration-, time-, and voltage-dependent manner. These results suggest that the compound 5 is an excellent candidate as an antiarrhythmic drug for atrial fibrillation.

• Journal of Plant Biotechnology
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• v.34 no.4
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• pp.313-322
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• 2007

Extract of Japanese red pine needles has been used in Asia pacific regions since long periods believing its valuable properties as tonic and ability of curing diseases of unidentified symptoms. Some selective compounds present in the extract and their effects were analyzed. Carbohydrates and vitamin c were identified using HPLC; terpenoid compounds by GC-MS; anti-bacterial analysis by paper discs, plates count and gastrointestinal motility by whole cell patch clamp. The extract is a mixture of compounds therefore its diverse effect was expected. Self-fermentation in extract proceeds after spontaneous appearance of yeast strains without inoculation. Effects and composition of the extract vary with varying period of self-fermentation. Extract inhibits the growth of bacteria dose dependently exhibiting its antibacterial properties however effectiveness increases with increase in fermentation period. The extract also can modulate gastrointestinal motility in murine small intestine by modulating pace maker currents in ICC mediated through ATP sensitive potassium channel.

• Molecules and Cells
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• v.22 no.1
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• pp.65-69
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• 2006

In murine gastrointestinal myocytes muscarinic stimulation activates nonselective cation channels via a G-protein and $Ca^{2+}$-dependent pathway. We recorded inward cationic currents following application of carbachol ($I_{CCh}$) to murine gastric myocytes held at -60 mV, using the whole-cell patch-clamp method. The properties of the inward cationic currents were similar to those of the nonselective cation channels activated by muscarinic stimulation in other gastrointestinal smooth muscle cells. CCh-induced $I_{CCh}$ and spontaneous decay of $I_{CCh}$ (desensitization of $I_{CCh}$) occurred. Unlike the situation in guinea pig gastric myocytes, desensitization was not affected by varying $[EGTA]_i$. Pretreatment with the PLC inhibitor (U73122) blocked the activation of $I_{CCh}$, and desensitization of $I_{CCh}$ was attenuated in PLC ${\beta}_1$ knock-out mice. These results suggest that the desensitization of $I_{CCh}$ in murine gastric myocytes is not due to a pathway dependent on intracellular $Ca^{2+}$ but to the PLC ${\beta}_1$ pathway.

• Animal cells and systems
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• v.15 no.3
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• pp.181-187
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• 2011

Transient receptor potential vanilloid type 1 (TRPV1) receptor plays an important role as a molecular detector of noxious signals in primary sensory neurons. Activity of TRPV1 can be modulated by the change in the environment such as redox state and extracellular cations. In the present study, we investigated the effect of the mercury chloride ($HgCl_2$) on the activity of TRPV1 in rat dorsal root ganglia (DRG) neurons using whole-cell patch clamp technique. Extracellular $HgCl_2$ reversibly reduced the magnitudes of capsaicin-activated currents ($I_{cap}$) in DRG neurons in a dose-dependent manner. The blocking effect of $HgCl_2$ was prevented by pretreatment with the reducing agent dithiothreitol (DTT). Inhibition of $I_{cap}$ by $HgCl_2$ was abolished by point mutation of individual cysteine residues located on the extracellular surface of TRPV1. These results suggest that three extracellular cysteines of TRPV1, Cys616, Cys634 and Cys621, are responsible for the oxidative modulation of $I_{cap}$ by $HgCl_2$.

• Archives of Pharmacal Research
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• v.29 no.10
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• pp.834-839
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• 2006

Torilin was purified from Torilis japonica (Houtt.) DC., and its effects on a rapidly activating delayed rectifier $K^+$ channel (hKv1.5), cloned from human heart and stably expressed in Ltk cells, as well as the corresponding $K^+$ current (the ultrarapid delayed rectifier, $I_{KUR}$) were assessed in human atrial myocytes. Using the whole cell configuration of the patch-clamp technique, torilin was found to inhibit the hKv1.5 current in time and voltage-dependent manners, with an $IC_50$ value of $2.51{\pm}0.34\;{\mu}M$ at +60 mV. Torilin accelerated the inactivation kinetics of the hKv1.5 channel, and slowed the deactivation kinetics of the hKv1.5 current, resulting in a tail crossover phenomenon. Additionally, torilin inhibited the hKv1.5 current in a use dependent manner. These results strongly suggest that torilin is a type of open-channel blocker of the hKv1.5 channel.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.249-255
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• 2018

Echinacoside, an active compound in the herb Herba Cistanche, has been reported to inhibit glutamate release. In this study, we investigated the effects of echinacoside on spontaneous excitatory synaptic transmission changes induced by 4-aminopyridine (4-AP), by using the in vitro rat hippocampal slice technique and whole-cell patch clamp recordings from CA3 pyramidal neurons. Perfusion with echinacoside significantly suppressed the 4-AP-induced epileptiform activity in a concentration-dependent manner. Echinacoside reduced 4-AP-induced increase in frequency of spontaneous excitatory postsynaptic currents (sEPSCs) but it did not affect the amplitude of sEPSCs or glutamate-activated currents, implicating a presynaptic mechanism of action. Echinacoside also potently blocked sustained repetitive firing, which is a basic mechanism of antiepileptic drugs. These results suggest that echinacoside exerts an antiepileptic effect on hippocampal CA3 pyramidal neurons by simultaneously decreasing glutamate release and blocking abnormal firing synchronization. Accordingly, our study provides experimental evidence that echinacoside may represent an effective pharmacological agent for treating epilepsy.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.3
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• pp.227-237
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• 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.

• The Korean Journal of Physiology and Pharmacology
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• v.23 no.5
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• pp.393-402
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• 2019

Aurora kinases inhibitors, including ZM447439 (ZM), which suppress cell division, have attracted a great deal of attention as potential novel anti-cancer drugs. Several recent studies have confirmed the anti-cancer effects of ZM in various cancer cell lines. However, there have been no studies regarding the cardiac safety of this agent. We performed several cytotoxicity, invasion and migration assays to examine the anti-cancer effects of ZM. To evaluate the potential effects of ZM on cardiac repolarisation, whole-cell patch-clamp experiments were performed with human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and cells with heterogeneous cardiac ion channel expression. We also conducted a contractility assay with rat ventricular myocytes to determine the effects of ZM on myocardial contraction and/or relaxation. In tests to determine in vitro efficacy, ZM inhibited the proliferation of A549, H1299 (lung cancer), MCF-7 (breast cancer) and HepG2 (hepatoma) cell lines with $IC_{50}$ in the submicromolar range, and attenuated the invasive and metastatic capacity of A549 cells. In cardiac toxicity testing, ZM did not significantly affect $I_{Na}$, $I_{Ks}$ or $I_{K1}$, but decreased $I_{hERG}$ in a dose-dependent manner ($IC_{50}$: $6.53{\mu}M$). In action potential (AP) assay using hiPSC-CMs, ZM did not induce any changes in AP parameters up to $3{\mu}M$, but it at $10{\mu}M$ induced prolongation of AP duration. In summary, ZM showed potent broad-spectrum anti-tumor activity, but relatively low levels of cardiac side effects compared to the effective doses to tumor. Therefore, ZM has a potential to be a candidate as an anti-cancer with low cardiac toxicity.