• The Korean Journal of Physiology and Pharmacology
• /
• 제18권4호
• /
• pp.341-346
• /
• 2014

Lubiprostone is a chloride ($Cl^-$) channel activator derived from prostaglandin $E_1$ and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid $EP_1$, $EP_2$, $EP_3$, and $EP_4$ antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. L-NG-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [$K^+$] channel blocker) and apamin (a calcium [$Ca^{2+}$]-dependent $K^+$ channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive $K^+$ channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive $K^+$ channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive $K^+$ channel through a prostanoid EP receptor-independent mechanism.

• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2707-2712
• /
• 2009

5-$HT_{3}$ receptor;5-$HT_{3A}$ receptor channel activity;Novel 5-$HT_{3}$ receptor channel current blockers;Chlorophenyl substituted piperazinylethylaminomethylpyrazoles; The 5-$HT_{3A}$ receptors are one of ligand-gated ion channels and are known to be involved in visceral pain, anxiety, or anticancer agent-induced nausea and vomiting. In present study, we designed novel skeletons based on the developed 5-$HT_{3}$ receptor antagonists and evaluated their effects on 5-$HT_{3A}$ receptor channel currents ($I_{5-HT}$) of a series of pyrazole derivatives having N-chlorophenylpiperazine functionality (6-9). We found that most of N-p-chlorophenyl substituted piperazinyl-pyrazole derivatives (7b, 7c, 7e and 7h) exhibited the high potency for the inhibition of $I_{5-HT}$, whereas the compound without chloride (6) or with m-chlorophenyl group (a serious of 8 and 9) showed the low potency. These result indicate that p-chlorophenyl group is might play an important role for increasing the inhibitory potency on $I_{5-HT}$.

• The Korean Journal of Physiology
• /
• 제28권2호
• /
• pp.143-150
• /
• 1994

The whole-cell mode of the patch clamp technique was used to study $Ca^{2+}-activated\;Cl^-\;current$ $(I_{Cl_{Ca}})$ in gastric antral myocytes. Extracellular application of caffeine evoked $Ca^{2+}-activated\;current$. In order to isolate the chloride current from background current, all known systems were blocked with specific blockers. The current-voltage relationship of caffeine-induced current showed outward rectification and it reversed at around $E_{Cl^-}$. The shift of reversal potential upon the alteration of external and internal chloride concentrations was well fitted with results which were calculated by the Nernst equation. Extracellular addition of N-phenylanthranilic acid and niflumic acid which are known anion channel blockers abolished the caffeine induced current. Intracellular application of a high concentration of EGTA also abolished this current. Application of c-AMP, c-GMP, heparin, or $AIF^-_4$ made no remarkable changes to this current. Sodium replacement with the impermeable cation N-methylglucamine or with $Cd^{2+}$ rarely affected this current. From the above results it is suggested that the caffeine induced current was a $Cl^-$ current and it was activated by intracellular $Ca^{2+}$.

• Molecules and Cells
• /
• 제37권5호
• /
• pp.418-425
• /
• 2014

Extracellular hypotonic stress can affect cellular function. Whether and how hypotonicity affects immune cell function remains to be elucidated. Macrophages are immune cells that play key roles in adaptive and innate in immune reactions. The purpose of this study was to investigate the role and underlying mechanism of hypotonic stress in the function of bone marrow-derived macrophages (BMDMs). Hypotonic stress increased endocytic activity in BMDMs, but there was no significant change in the expression of CD80, CD86, and MHC class II molecules, nor in the secretion of TNF-${\alpha}$ or IL-10 by BMDMs. Furthermore, the enhanced endocytic activity of BMDMs triggered by hypotonic stress was significantly inhibited by chloride channel-3 (ClC-3) siRNA. Our findings suggest that hypotonic stress can induce endocytosis in BMDMs and that ClC-3 plays a central role in the endocytic process.

• Animal cells and systems
• /
• 제7권1호
• /
• pp.75-79
• /
• 2003

Highly purified high performance thin layer chromatography (HPTLC) fractions containing a putative calcium influx factor (CIF) were prepared from the Jurkat cells and Xenopus oocytes in which $Ca^{2+}$ stores were depleted by thapsigargin treatment and from the yeast in which intracellular $Ca^{2+}$ stores were also depleted by genetic means. Microinjection of the fractions has been shown to elicit $Ca^{2+}$ dependent currents in Xenopus oocytes. The nature of the membrane currents evoked by the putative CIF appeared to be carried by chloride ions since the current was blocked by the selective chloride channel blocker 1 mM niflumic acid and its reversal potential was about -24 mV. Injection of the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N, N, N',N'-tetraacetic acid (BAPTA) eradicated the current activities, suggesting the current responses are entirely $Ca^2$-dependent. Moreover, the currents were sensitive to the removal of extracellular calcium, indicating the dependence on calcium entry through the plasma membrane calcium entry channels. CIF activities were insensitive to protease, heat, and acid treatments and to Dische-reaction whereas the activities were sensitive to nucleotide pyrophosphatase and hydrazynolysis. The fraction might have a sugar because it was sensitive to Molisch test and Seliwaniff's resorcinol reaction. From the above results, CIF as a small and stable molecule seems to have pyrimidine, pyrophosphate, and a sugar moiety.oiety.

• 대한화학회지
• /
• 제37권8호
• /
• pp.695-701
• /
• 1993

25$^{\circ}C$에서 메탄올, 에탄올, 아세톤 이성분 혼합수용액과 물, 메탄올에서의 가용매분해반응 속도 상수를 결정하고, 이들 속도자료를 Grunwald-Winstein 식과 Kivinen 관계식을 이용하여 해석하였다. 또한 물과 메탄올에서의 속도론적 용매 동위원소 효과와 알코올-물 혼합용매계에서 생성물 선택성 값을 결정하였다. 염화 2-티오펜술포닐의 가용매 분해반으에 대한 속도론적 용매 동위원소 효과는 메탄올과 물에서 각가 2.24와 1.47이었다. 에탄올-물에서의 술포닐 에스테르 형성에 대한 선택성 값은 최대값을 나타내었다. 메탄올과 물에서의 속도론적 용매 동위원소 효과, 알코올 수용액에서의 선택성 자료와 용매효과로부터, 본 연구에서의 반응은 극성이 낮은 용매계에서는 일반염기 촉매반응과 또는 S$_A$N 반응이 유리하고, 극성이 큰 용매계에서는 S$_N$2 반응의 유리한 반응으로 진행되는 것으로 제안하였다.

• 대한토목학회논문집
• /
• 제28권5A호
• /
• pp.729-735
• /
• 2008

건전하게 설계 시공된 콘크리트는 충분한 내구성 및 장기수명을 갖는 것으로 알려졌다. 그러나 저자의 기존 연구에 의하면 콘크리트 표면에 존재하는 균열은 염소이온의 침투에 대한 빠른 침투 통로가 되어 내구성능을 저하시킬 수 있는 것으로 나타났다. 균열을 제어하기 위하여 설계적 측면에서 높은 철근비로 균열폭을 감소시킬수는 있으나, 이러한 균열이 실질적으로 내구성을 저하시키는데에 따른 검토 및 내구성 향상을 유도할 수 있는 방법이 필요하다. 표면도장공법은 균열폭이 작은 경우에 균열을 실링하여 염소이온 침투를 차단하는데 가장 간단한 방법중의 하나로 간주될 수 있다. 그래서 본 연구는 표면도장공법으로 미세균열의 개구를 통한 염소이온 침투를 제어할 수 있는지를 고찰하였다. 실험변수로 침투재와 도포재의 단일 적용과 복합적용이 실험변수로 고려되었으며, 급속 염소이온 침투 실험을 통하여 균열대비 염소이온 침투깊이를 검토하였다. 실험결과에 의하면 침투재는 균열 실링효과를 기대할 수 없었으나, 도막재는 0.06 mm, 침투재와 도막재를 혼합사용하면 0.08 mm이내의 균열폭에서 염소이온 침투를 제어할 수 있었다.

• 동의생리병리학회지
• /
• 제27권1호
• /
• pp.112-117
• /
• 2013

We studied the modulation of pacemaker activities by Samchulkunbi-tang (SCKB) in cultured interstitial cells of Cajal (ICC) from murine small intestine with the whole-cell patch-clamp technique. Externally applied SCKB produced membrane depolarization in the current-clamp mode. The pretreatment with $Ca^{2+}$-free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker potentials and suppressed the SCKB-induced action. The application of flufenamic acid (a nonselective cation channel blocker) abolished the generation of pacemaker potentials by SCKB. However, the application of niflumic acid (a chloride channel blocker) did not inhibit the generation of pacemaker potentials by SCKB. In addition, the membrane depolarizations were inhibited by not only GDP-${\beta}$-S, which permanently binds G-binding proteins, but also U-73122, an active phospholipase C inhibitor. These results suggest that SCKB modulates the pacemaker activities by nonselective cation channels and external $Ca^{2+}$ influx and internal $Ca^{2+}$ release via G-protein and phospholipase C-dependent mechanism. Therefore, the ICC are targets for SCKB and their interaction can affect intestinal motility.

• 한국가시화정보학회지
• /
• 제10권1호
• /
• pp.34-39
• /
• 2012

In the present study, oxygen transfer process across gas-liquid interface in a Y-shape micro-channel is quantitatively visualized using the micro laser induced fluorescence (${\mu}$-LIF) technique. Diffusion coefficient of Oxygen ($D_L$) is estimated based on the experimental results and compared to its theoretical value. Tris ruthenium (II) chloride hexahydrate was used as the oxygen quenchable fluorescent dye. A light-emitting diode (LED) with wavelength of 450 nm was used as the light source and phosphorescence images of fluorescent dye were captured by a CMOS high speed camera installed on the microscope system. Water having dissolved oxygen (DO) value of 0% and pure oxygen gas were injected into the Y-shaped microchannel by using a double loading syringe pump. In-situ pixel-by-pixel calibration was carried out to obtain Stern-Volmer plots over whole flow field. Instantaneous DO concentration fields were successfully mapped according to Stern-Volmer plots and DL was calculated as $2.0675{\times}10^{-9}\;m^2/s$.

• Biomolecules & Therapeutics
• /
• 제16권4호
• /
• pp.328-335
• /
• 2008

This study was undertaken to investigate whether honokiol could enhance the pentobarbitalinduced sleeping behaviors through $\gamma$-aminobutyric acid (GABA) receptor $Cl^-$ channel activation. Thirty minutes after the oral administration of honokiol, mice were received sodium pentobarbital (42 mg/kg, i.p.). The time elapsed from pentobarbital injection to the loss of the righting reflex was taken as sleeping latency. The time elapsed between the loss and voluntary recovery of the righting reflex was considered as the total sleeping time. Western blot technique and $Cl^-$ sensitive fluorescence probe were used to detect the expression of $GABA_A$ receptor subunits and $Cl^-$ influx in the primary cultured cerebellar granule cells. Honokiol (0.1 and 0.2 mg/kg) prolonged the sleeping time induced by pentobarbital (42 mg/kg) in a dosage-dependent manner. Honokiol (20 and 50 ${\mu}M$) increased $Cl^-$ influx in primary cultured cerebellar granule cells, and selectively increased the $GABA_A$ receptor $\alpha$-subunit expression, but had no effect on the abundance of $\beta$ or $\gamma$-subunits. Chronic treatment with 20 ${\mu}M$ honokiol in primary cultured cerebellar neurons did not affect the abundance of GAD65/67. The results suggested that honokiol could potentiate pentobarbital-induced sleeping through $GABA_A$ receptor $Cl^-$ channel activation.