• Biomolecules & Therapeutics
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• 제9권1호
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• pp.40-45
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• 2001

The activity of taurine transporter is affected by various extracellular stimuli such as ion, hormone and stress. To assess effects of steroid hormones antral cyclosporin A (CsA) on the taurine transporter activity, murine monocytic RAW264.7 cell line was stimulated with dexamethasone (DM), triamcinolone (TA), cortisone (CS), hydrocortisone (HCS), prednisone (PSN), prednisolone (PSL) and methylprednisolone (MPSL) in the presence of 12-0-tetradecanoylphorbol-13-acetate(TPA). Treatment of TPA on the cell line led to significant reduction of taurine transporter activity. However, in case of stimulation of the cells with steroid hormones in the presence of TPA, all of them recovered TPA-induced reduction of the taurine transporter activity. Treatment of the cells with CsA led to significant reduction of the taurine transporter activity. Ionomycin (IM) recovered the reduced taurine transporter activity by CsA, but failed in the presence of EDTA, a calcium chelating agent. These results showed that glucocorticoid hormone recovered TPA-induced reduction of taurine transporter activity and that IM recovered CsA-induced reduction of the transporter activity by increasing intracellular free $Ca^{++}$ concentration.n.

• The Korean Journal of Physiology
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• 제28권2호
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• pp.151-157
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• 1994

Intracellular free $Ca^{2+}$ contributes to regulation of various events occurring in vascular smooth muscle cells. One of these events is modulating the membrane iou currents. Single smooth muscle cells were isolated from rabbit mesenteric artery. Three kinds of $Ca^{2+}-activated\;current$ were studied with the patch clamp method. $Ca^{2+}-activated\;K^+\;current$ with a large oscillation was recorded in the depolarized potential range. The single channel conductance of this current was about 250 pS. It was abolished by replacing intracellular $K^+\;with\;Cs^+$. A $Ca^{2+}-activated$ nonselective cation current was observed in both the depolarized and hyperpolarized potential ranges. And it was blocked by replacement of extracellular $Na^+$ with N-methylglucamine (NMG) or extracellular application of $Cd^{2+}$. $Ca^{2+}-activated\;Cl^-\;current$ was revealed in the whole voltage range and was blocked by niflumic acid. These results indicate that at least three kinds of $Ca^{2+}-activated$ ionic currents exist in smooth muscle cells from rabbit superior mesenteric artery.

• The Korean Journal of Physiology and Pharmacology
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• 제12권2호
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• pp.43-49
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• 2008

Flavonoids have been shown to affect calcium signaling in neurons. However, there are no reports on the effect of apigenin on glutamate-induced calcium signaling in neurons. We investigated whether apigenin affects glutamate-induced increase of free intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) in cultured rat hippocampal neurons, using fura-2-based digital calcium imaging and microfluorimetry. The hippocampal neurons were used between 10 and 13 days in culture from embryonic day 18 rats. Pretreatment of the cells with apigenin ($1{\mu}M$ to $100{\mu}M$) for 5 min inhibited glutamate ($100{\mu}M$, 1 min) induced $[Ca^{2+}]_i$ increase, concentration-dependently. Pretreatment with apigenin ($30{\mu}M$) for 5 min significantly decreased the $[Ca^{2+}]_i$ responses induced by two ionotropic glutamate receptor agonists, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA, $10{\mu}M$, 1 min) and N-methyl-D-aspartate (NMDA, $100{\mu}M$, 1 min), and significantly inhibited the AMPA-induced peak currents. Treatment with apigenin also significantly inhibited the $[Ca^{2+}]_i$ response induced by 50 mM KCl solution, decreased the $[Ca^{2+}]_i$ responses induced by the metabotropic glutamate receptor agonist, (S)-3,5-dihydroxy-phenylglycine (DHPG, 100 $[Ca^{2+}]_i$, 90 s), and inhibited the caffeine (10 mM, 2 min)-induced $[Ca^{2+}]_i$ responses. Furthermore, treatment with apigenin ($30{\mu}M$) significantly inhibited the amplitude and frequency of 0.1 mM $[Mg^{2+}]_o$-induced $[Ca^{2+}]_i$ spikes. These data together suggest that apigenin inhibits glutamate-induced calcium signaling in cultured rat hippocampal neurons.

• International Journal of Oral Biology
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• 제31권3호
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• pp.99-105
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• 2006

Von Ebner's glands (vEG) are minor salivary glands associated with circumvallate and foliate papilla. The secretions of vEG consist of microenvironment of the taste buds in the circumvallate and foliate papillae, and thus saliva from vEG plays a role in the perception of taste. The $Ca^{2+}$ signaling system in rat vEG acinar cell was examined using the $Ca^{2+}$-sensitive fluorescent indicator Fura-2. Agonist-induced increase in intracellular $Ca^{2+}\;([Ca^{2+}]_i)$ was stimulated by carbachol (CCh) and substance P (SP), but not by norepinephrine (NE), and recovered to control levels by their receptor antagonists dose-dependently. The effects were also observed in $Ca^{2+}$-free medium, suggesting mobilization from intracellular $Ca^{2+}$ store. These results in the vEG acinar cell indicate that 1) $[Ca^{2+}]_i$ is at least regulated by muscarinic and neurokininergic (NK1) receptors; 2) the increases in $[Ca^{2+}])i$ activated by CCh and SP are mainly mediated by discharge of cytosolic calcium pool.

• The Korean Journal of Physiology and Pharmacology
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• 제3권2호
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• pp.199-205
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• 1999

Vibrio vulnificus cytolysin caused platelet cytolysis and increased intracellular calcium concentration $([Ca^{2+}]_i)$ of rat platelets in a concentration-dependent manner. In the presence of V. vulnificus cytolysin (3 HU/ml), lactate dehydrogenase (LDH) activity was increased from $1.3{\pm}0.4%$ of control to $64.3{\pm}3.4%$ in platelet suspension buffer. In $Ca^{2+}-free$ platelet suspension buffer, however, V. vulnificus cytolysin did not induce $[Ca^{2+}]_i$ increase and LDH release. Addition of EGTA (2 mM) to suspension buffer after the initial $Ca^{2+}$ influx reversed $[Ca^{2+}]_i$ to the control level. However, a $Ca^{2+}$ channel blocker verapamil $(20\;{\mu}M)$ or mefenamic acid $(20\;{\mu}M)$ did not inhibit V. vulnificus cytolysin-induced $[Ca^{2+}]_i$ increase and LDH release. Divalent cations such as $Co^{2+},\;Cd^{2+}\;or\;Mn^{2+}$ (2 mM each) also did not alter V. vulnificus cytolysin-induced $[Ca^{2+}]_i$ increase and LDH release. V. vulnificus cytolysin (3 HU/ml)-induced calcium influx was completely blocked by lanthanum (2 mM). Lanthanum (2 mM) also completely blocked V. vulnificus cytolysin (3 HU/ml)-induced LDH release. Osmotic protectants such as, raffinose, sucrose or PEG600 (50 mM each) did not inhibit the lytic activity of V. vulnificus cytolysin. In conclusion, lanthanum sensitive $Ca^{2+}$ influx plays a significant role in Vibrio vulnificus cytolysin-induced platelet cytolysis and thrombocytopenia in V. vulnificus infection.

• Archives of Pharmacal Research
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• 제27권5호
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• pp.524-530
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• 2004

Epilepsy or the occurrence of spontaneous recurrent epileptiform discharges (SREDs, seizures) is one of the most common neurological disorders. Shift in the balance of brain between excitatory and inhibitory functions due to different types of structural or functional alterations may cause epileptiform discharges. N-Methyl-D-aspartate (NMDA) receptor dysfunctions have been implicated in modulating seizure activities. Seizures and epilepsy are clearly dependent on elevated intracellular calcium concentration ([C $a^{2+}$]$_{i}$ ) by NMDA receptor activation and can be prevented by NMDA antagonists. This perturbed [C $a^{2+}$]$_{i}$ levels is forerunner of neuronal death. However, therapeutic tools of elevated [C $a^{2+}$]$_{i}$ level during status epilepticus (SE) and SREDs have not been discovered yet. Our previous study showed fast inhibition of ginseng total saponins and ginsenoside R $g_3$ on NMDA receptor-mediated [C $a^{2+}$]$_{i}$ in cultured hippocampal neurons. We, therefore, examined the direct modulation of ginseng on hippocampal neuronal culture model of epilepsy using fura-2-based digital $Ca^{2+}$ imaging and neuronal viability assays. We found that ginseng total saponins and ginsenoside R $g_3$ inhibited $Mg^{2+}$ free-induced increase of [C $a^{2+}$]$_{i}$ and spontaneous [C $a^{2+}$]$_{i}$ oscillations in cultured rat hippocampal neurons. These results suggest that ginseng may playa neuroprotective role in perturbed homeostasis of [C $a^{2+}$]$_{i}$ and neuronal cell death via the inhibition of NMDA receptor-induced SE or SREDs.d SE or SREDs..

• Biomolecules & Therapeutics
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• 제7권3호
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• pp.227-233
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• 1999

The effects of 2-bromo-3-(3,5-tert-butyl-4-hydroxylphenyl)-1,4-naphthalenedione(TPN2), a synthetic vitamin K derivative, on platelet aggregation and its action mechanisms were investigated in rat platelet. TPN2 inhibited the platelet aggregation induced by collagen($10\mu\textrm{g}$/ml), thrombin(0.1 U/ml), A23187($10\mu\textrm{M}$) and arachidonic acid($100\mu\textrm{M}$) in concentration-dependent manner with $IC_{50}$ values of 6.5$\pm$1.3, 59.3$\pm$4.5, 13.0$\pm$2.37 and 2.9$\pm$$1.0\mu\textrm{M}$, respectively. Collagen-induced serotonin release was significantly reduced by TPN2. The elevation of intracellular free $Ca^{2+}$ concentration ([$Ca^{2+}$]i) by collagen stimulation was greatly decreased by the pretreatment of TPN2, which was due to the inhibition of calcium release from intracellular store and influx from outside of the cell. TPN2 also significantly reduced the thromboxane $A_2$($TXA_2$) formation in a concentration-dependent manner. The collagen-induced arachidonic acid (AA) release in [$^3H$]-AA incorporated platelet, an indicative of the phospholipase $A_2$ activity, was decreased by TPN2 pretreatment. TPN2 significantly inhibited the activity of thromboxane synthase, but did not affect the cyclooxygenase activity. From these results. it is suggested that TPN2 exert its antiplatelet activity through the inhibition of the intra-cellular $Ca^{2+}$ mobilization and the decrease of the $TXA_2$ synthesis.

• 대한약리학회지
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• 제28권1호
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• pp.91-102
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• 1992

칼슘을 함유하는 반응액에서 arachidonic acid는 뚜렷하게 superoxide와 $H_2O_2$의 생성을 자극하였고 NADPH oxidase를 활성화하였다. 칼슘이 없는 반응액에서 NADPH oxidase에 대한 arachidonic acid의 자극 작용은 나타나지 않았다. Arachidonic acid에 의하여 자극된 respiratory burst는 EGTA, TMB-8, verapamil, diltiazem, nifedipine, dibucaine, lidocaine, CCCP, 2,4-dinitrophenol, sodium arsenate, chlorpromazine, theophylline, $HgCl_2$, PCMB와 PCMBSA에 의하여 억제되었으나, tetrodotoxin, tetraethyl ammonium chloride와 procaine의 영향은 받지 않았다. EGTA는 거의 완전히 arachidonic acid에 의한 ${\beta}-glucuronidase$의 유리를 억제하였으며, verapamil, CCCP와 theophylline은 약간 억제하였으나, 이에 반하여 dibucaine은 유의한 효과를 나타내지 않았다. Arachidonic acid는 중성호성 백혈구로 부터 칼슘을 유리시켰으며, 이는 TMB-8에 의하여 감소되었다. Arachidonic acid에 의한 세포내 유리 칼슘 농도의 상승은 EGTA와 CCCP에 의하여 억제되었고 TMB-8에 의하여 약간 억제되었다. Arachidonic acid와 verapamil 또는 arachidonic acid와 dibucaine의 동시 첨가에 의하여 상승된 세포내 유리 칼슘 농도의 양은 arachidonic acid 단독에 의한 것보다 현저하였다. 이상의 결과로 부터 다양한 생화학적 변화가 arachidonic acid에 의하여 활성화된 중성호성 백혈구의 기능 표현에 관여할 것으로 시사된다. Arachidonic acid는 세포내 칼슘 저장고로부터 칼슘유리를 자극하여 세포내 유리 칼슘 농도를 상승시킬 것으로 추정된다. 중성호성 백혈구의 활성화증에 칼슘 유입과 유출은 동시에 이루어질 것으로 추정된다.

• Biomolecules & Therapeutics
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• 제26권6호
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• pp.546-552
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• 2018

A comprehensive collection of proteins senses local changes in intracellular $Ca^{2+}$ concentrations ($[Ca^{2+}]_i$) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular $Ca^{2+}$ concentrations in cat esophageal smooth muscle cells. To measure $[Ca^{2+}]_i$ levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in $[Ca^{2+}]_i$ in the cells. Pretreatment with EGTA, an extracellular $Ca^{2+}$ chelator, decreased the S1P-induced increase in $[Ca^{2+}]_i$, and an L-type $Ca^{2+}$-channel blocker, nimodipine, decreased the effect of S1P. This indicates that $Ca^{2+}$ influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an $InsP_3$ receptor blocker, the S1P-evoked increase in $[Ca^{2+}]_i$ was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of $G_i$-protein, suppressed the increase in $[Ca^{2+}]_i$ evoked by S1P. These results suggest that the S1P-induced increase in $[Ca^{2+}]_i$ in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of $Ca^{2+}$ from the $InsP_3$-sensitive $Ca^{2+}$ pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular $Ca^{2+}$ via the L type $Ca^{2+}$ channel, which was dependent on activation of the $S1P_4$ receptor coupled to PTX-sensitive $G_i$ protein, via phospholipase C-mediated $Ca^{2+}$ release from the $InsP_3$-sensitive $Ca^{2+}$ pool in cat esophageal smooth muscle cells.

• Journal of Microbiology
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• 제34권3호
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• pp.253-269
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• 1996

Infection of fish cells with IHNV resulted in gradual increase in cytosolic free Ca$\^$2+/ concentration ([Ca$\^$2+/)] in CHSE, gradual decrease in [Ca$\^$2+/] in FHM, and no significant change in RTG cells. The degree of [Ca$\^$2+/] increase or decrease was dependent on the amount of infectious virus, and these [Ca$\^$2+/] variations were maximal at 16 hours after virus infection (p. i.) in both cell lines. When the fish cells were infected with inactivated IHNV, evident variation in [Ca$\^$2+/] was not observed. Thus, infectivity of IHNV appears to correlate with changes in [Ca$\^$2+/] in virus-infected cells. These IHNV-induced [Ca$\^$2+/] changes were partially blocked by cycloheximide, but not affected by cordycepin. It seems to be that virus-induced Ca$\^$2+/ variations were more related with protein synthesis than RNA synthesis. Various Ca$\^$2+/ related drugs were used in search for the mechanisms of the [Ca$\^$2+/], changes following IHNV infection of CHSE cells. Decreasing extracellular Ca$\^$2+/ concentration or blocking Ca$\^$2+/ influx from extracellular media inhibited the IHNV-induced increase in [Ca$\^$2+/], in CHSE cells. Similar results were obtained with intracellular Ca$\^$2+/ sources are important in IHNV-induced [Ca$\^$2+/] increase in CHSE cells.