• Korean Journal of Veterinary Research
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• v.36 no.1
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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.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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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.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.1
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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.

• YAKHAK HOEJI
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• v.45 no.6
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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.

• Archives of Pharmacal Research
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• v.18 no.1
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• pp.27-30
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• 1995

The Hantzsh reaction of 7-hydroxy-8-methoxy-2-oxo-2H-benzopyran-6-carboxaldehyde (1) with ethyl acetoacetate and ammonia yields the dihydropyridine derivative 2 together with the pyridine derivative 3 and the eight membred ring derivative 4. Reaction of 1 with ethyl cyanoacetate and malononitrile gives the iminodicoumarin derivatives 5 and 6 respectiely. The latter compound was reacted with butan-2-one and acetophenone to produce the Michael adduct 71, b and the 2-aminopyridine derivatives 8a, b.

• Proceedings of the PSK Conference
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• 2003.10b
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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.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.342.1-342.1
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• 2002

6.7-Dicholroquinoline-5.8-dione reacted with 2-aminopyridine derivatives, Out of the four possible products which could be achieved in this reaction. condensation and rearrangement product. 4a.10.11-triazabenzo［3.2-a］ fluorine-5.6-dione was obtained as major product. The definite structure was identified with X-ray crystallographic study. (omitted)

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.6
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• pp.617-623
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• 2017

The vascular actions and mechanisms of taurine were investigated in the isolated human radial artery (RA). RA rings were suspended in isolated organ baths and tension was recorded isometrically. First, a precontraction was achieved by adding potassium chloride (KCl, 45 mM) or serotonin (5-hydroxytryptamine, 5-HT, $30{\mu}M$) to organ baths. When the precontractions were stable, taurine (20, 40, 80 mM) was added cumulatively. Antagonistic effect of taurine on calcium chloride ($10{\mu}M$ to 10 mM) -induced contractions was investigated. Taurine-induced relaxations were also tested in the presence of the $K^+$ channel inhibitors tetraethylammonium (1 mM), glibenclamide ($10{\mu}M$) and 4-aminopyridine (1 mM). Taurine did not affect the basal tone but inhibited the contraction induced by 5-HT and KCl. Calcium chloride-induced contractions were significantly inhibited in the presence of taurine (20, 40, 80 mM) (p<0.05). The relaxation to taurine was inhibited by tetraethylammonium (p<0.05). However, glibenclamide and 4-aminopyridine did not affect taurine -induced relaxations. Present experiments show that taurine inhibits 5-HT and KCl -induced contractions in RA, and suggest that large conductance $Ca^{2+}$-activated $K^+$ channels may be involved in taurine -induced relaxation of RA.

• YAKHAK HOEJI
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• v.34 no.6
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• pp.422-428
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• 1990

2,3-Dibromo-1,4-naphthoquinone was reacted with p-aminobenzoic acid, 2-aminopyridine, 2-amino-4-metylpyridine, m-nitroaniline, sulfathiazol, p-chloroaniline, phenetidine and 2-bromo-3-(N-arylamino)-1,4-naphthoquinones($1{\sim}8$). 2,3-Epoxy-2,3-dihydro-1,4-naphthoquinone was also reacted with p-amonobenzoic acid, p-toluidine, p-chloroaniline, m-chloroaniline, m-nitroaniline, p-phenetidine, N,N-dimethyl-1,4-pheylenediamine as a ring opening and dehydogenation to form 2-hydroxy-3-(N-arylamino)-naphthoquinones ($9{\sim}16$) in good yield. These new compounds($1{\sim}16$) are expected to have a biological activities such as anticoagulant and cytotoxic.

• Archives of Pharmacal Research
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• v.15 no.4
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• pp.317-321
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• 1992

Furoyldroximoyl chloride 3d reacted with 2-aminopyridine, 2-aminopyrimidine. O-aminophenol, O-phenylenediamine and aminothiophenol to afford imidazo [1, 2-a]pyridine 6. imidazo[1, 2-a]pyrimidine 8, benzoxadiazine 10, nitrosobenzopyrizine 13a and nitrosobenzothiazine 13b, respectively. Isoxazoline 18 and pyrrolidino[3, 4-d]isoxazolin-4, 6-dione derivatives 19a and 19b obtained by the reaction of 3 with acrylonitrile and N-arylmaleimide. Hydroximoyl chloride 3 reacted with thiophenol and sodium benzene-sulfinate to yield furylglyoxaloxime 16a and 16b, respectively. Hydroximoyl chloride 3 reacted also with some active methylene compound to give isoxazole derivatives 20-23, respectively.