• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2247-2248
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• 2013

• The Korean Journal of Physiology and Pharmacology
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• 제4권5호
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• pp.385-391
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• 2000

Using the patch-clamp technique, we investigated the alteration of 4-aminopyridine(4-AP)-sensitive, voltage-dependent $K^+$ channel (Kv) in the mesenteric arterial smooth muscle cell (MASMC) of renovascular hypertensive model, one-kidney one-clip Goldblatt hypertensive rat (GBH). To isolate $K_V$ current, internal pipette solution contained 5 mM ATP and 10 mM EGTA. Under these condition, MASMC was depolarized by 4-AP, but charybdotoxin did not affect membrane potential. Membrane potential of hypertensive cell $(-40.3{\pm}3.2\;mV)$ was reduced when compared to that of normotensive cell $(-59.5{\pm}2.8\;mV).$ Outward $K^+$ current of hypertensive cell was significantly reduced when compared to normotensive cell. At 60 mV, the outward currents were $19.10{\pm}1.91$ and $14.06{\pm}1.05$ pA/pF in normotensive cell and hypertensive cell respectively. 4-AP-sensitive $K^+$ current was also smaller in hypertensive cell $(4.28{\pm}0.38\;pA/pF)$ than in normotensive cell $(7.65{\pm}0.52\;pA/pF).$ The values of half activation voltage $(V_{1/2})$ and slope factor (k1) as well as the values of half inactivation voltage $(V_{1/2})$ and slope factor (k1) were virtually similar between GBH and NTR. These results suggest that the decrease of 4-AP-sensitive $K^+$ current contributes to a depolarization of membrane potential, which leads to development of vascular tone in GBH.

• The Korean Journal of Physiology and Pharmacology
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• 제7권1호
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• pp.25-28
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• 2003

Ion channel inhibitors are widely used for pharmacological discrimination between the different channel types as well as for determination of their functional role. In the present study, we tested the hypothesis that 4-aminopyridine (4-AP) could affect the large conductance $Ca^{2+}$-activated $K^+$ channel ($BK_{Ca}$) currents using perforated-patch or cell-attached configuration of patch-clamp technique in the rabbit pulmonary arterial smooth muscle. Application of 4-AP reversibly inhibited the spontaneous transient outward currents (STOCs). The reversal potential and the sensitivity to charybdotoxin indicated that the STOCs were due to the activation of $BK_{Ca}$. The $BK_{Ca}$ currents were recorded in single channel resolution under the cell-attached mode of patch-clamp technique for minimal perturbation of intracellular environment. Application of 4-AP also inhibited the single $BK_{Ca}$ currents reversibly and dose-dependently. The membrane potential of rabbit pulmonary arterial smooth muscle cells showed spontaneous transient hyperpolarizations (STHPs), presumably due to the STOC activities, which was also inhibited by 4-AP. These results suggest that 4-AP can inhibit $BK_{Ca}$ currentsin the intact rabbit vascular smooth muscle. The use of 4-AP as a selective voltage-dependent $K^+$ (KV) channel blocker in vascular smooth muscle, therefore, must be reevaluated.

• The Korean Journal of Physiology and Pharmacology
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• 제1권6호
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• pp.681-690
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• 1997

Loss of synaptic transmission and accumulation of extracellular $K^+([K^+]_O)$ are the key features in ischemic brain damage. Here, we examined the effects of several $K^+$channel modulators on the early ischemic changes in population spike (PS) and $[K^+]_o$ in the CA1 pyramidal layer of the rat hippocampal slice using electrophysiological techniques. After onset of anoxic aglycemia (AA), orthodromic field potentials decreased and disappeared in $3.3{\pm}0.22\;min$ $(mean{\pm}SEM,\;n=40)$. The hypoxic injury potential (HIP), a transient recovery of PS appeared at $6.0{\pm}0.25\;min$ (n=40) in most slices during AA and lasted for $3.3{\pm}0.43\;min$. $[K^+]_o$ increased initially at a rate of 0.43 mM/min (Phase 1) and later at a much faster rate (12.45 mM/min, Phase 2). The beginning of Phase 2 was invariably coincided with the disappearance of HIP. Among $K^+$ channel modulators tested such as 4-aminopyridine (0.03, 0.3 mM), tetraethylammonium (0.1 mM), NS1619 $(0.3{\sim}10\;{\mu}M)$, niflumic acid (0.1 mM), glibenclamide $(40\;{\mu}M)$, tolbutamide $(300\;{\mu}M)$ and pinacidil $(100\;{\mu}M)$, only 4-aminopyridine (0.3 mM) induced slight increase of $[K^+]_o$ during Phase 1. However, none of the above agents modulated the pattern of Phase 2 in $[K^+]_o$ in response to AA. Taken together, the experimental data suggest that 4-aminopyridine-sensitive $K^+$channels, large conductance $Ca^{2+}-activated$ $K^+$ channels and ATP-sensitive $K^+$ channels may not be the major contributors to the sudden increase of $[K^+]_o$ during the early stage of brain ischemia, suggesting the presence of other routes of $K^+$ efflux during brain ischemia.

• 대한수의학회지
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• 제36권1호
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• pp.83-91
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• 1996

Activation of $K^+$ channels induces relaxation of smooth muscles by reducing electrical excitability and cytosolic free $Ca^{2+}$ level. ${\beta}$-adrenergic agonist isoproterenol is known to induce relaxation of the uterine smooth muscle by membrane hyperpolarization and $K^+$ efflux. Recently it is suggested that the activity of $Ca^{2+}$-activated $K^+$ channel was increased by isoproterenol in the uterine myocytes isolated from myometrium of the pregnant rat. However, the type of $K^+$ channel mediating the relaxant effect of isopreterenol in the tissue level has not yet studied. In this work, we investigated the type of $K^+$ channels involved in the isoproterenol-induced relaxation of uterine smooth muscle by measuring the integrated insometric tension of the estrogen-treated isolated nonpregnant rat uterus. Contraction of uterine tissue was induced by oxytocin (0.2nM, 2~3 contractions/min) or high KCl(20~80mM). The result are as follows : 1. Isoproterenol($10^{-10}{\sim}10^{-4}M$) inhibited oxytocin-induced contraction of isolated rat uterus($EC_{50}=1.17{\times}10^{-10}M$). 2. Isoproterenol($10^{-10}{\sim}10^{-4}M$) effectively inhibited uterine contraction induced by low KCl(20~40mM) but little those induced by high KCl(60~80mM). 3. Relaxant effect of isoproterenol($10^{-10}{\sim}10^{-4}M$) on 0.2nM oxytocin-induced contraction was effectively reduced by 4-aminopyridine(3, 10mM) but little by TEA(10~30mM), $Ba^{2+}$($1{\sim}30{\mu}M$) and glibenclamide($100{\mu}M$). Our data suggest that the relaxant effect of isoproterenol is mediated by the $K^+$ channel(s) which can be blocked by 4-aminopyridine.

• Bulletin of the Korean Chemical Society
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• 제27권7호
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• pp.1053-1055
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• 2006

• The Korean Journal of Physiology and Pharmacology
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• 제22권3호
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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.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.86-87
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• 2012

폴리도파민이 다양한 표면을 개질할 수 있다는 것이 보고된 이래로, 폴리도파민을 이용한 다양한 응용 연구들이 계속되어 왔다. 본 연구에서는 이러한 폴리도파민을 이용하여 다양한 물질들로 오염된 물을 간단하고 효과적으로 정제하는 방법을 보고한다. 마이크로 크기의 실리카 비드에 폴리도파민을 코팅하여 흡착제로 사용하였으며, 이 흡착제가 다양한 중금속(Cu, Cr, Hg, Pb), 유기물질(4-Aminopyridine), 방사성 동위원소(Lutetium-177)를 효과적으로 흡착함을 확인하였다.

• 약학회지
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• 제45권6호
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• pp.570-574
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• 2001

In order to discover new useful NSAIDs, novel N-substituted 1,2-benzisothiazoline-3-one 1,1- dioxide derivatives, which can exhibit potentially antiinflammatory activity were synthesized. 1,2-Benz-isothiazoline-3-one-N-acetic acids 6a, b were obtained from monochloroacetic acid and sodium 1,2-benz-isothiazoline-3-ones in DMF by N-alkylation reaction. N-Substituted 1,2-benzisothiazoline-3-one 1,1-dioxide derivatives 7a-e were synthesized through the coupling of compound 6a, b and several amines (aniline, 2- aminopyridine , 2-aminothiazole, 2-aminotetrazole) with dicyclohexylcarbodiimide in methyl e no chloride.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.175.3-175.3
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• 2003

2-Phenyl-1, 8-naphthyridin-4-ones had been synthesized for their cytotoxic activity. Substituted acetophenone was treated with NaH and diethyl carbonate to give ethyl benzoylacetates, which was reacted with substituted 2-aminopyridine and PPA to yield 2-phenylpyridopyrimidine-4-ones. These compounds was heated at $350^\times$C in liquid paraffin to afford final compounds, 2-phenyl-1 , 8-naphthyridin-4-ones.