• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.151-156
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• 1991

In order to construct a yeast strain having high ethanol tolerance together with good lactose fermentation ability, the protoplast fusion using Saccharomyces cerevisiae STV 89 and Kluyveromyces fragilis CBS 397 was carried out. Auxotrophic mutants of K. fragilis were obtained as a selection marker by treatment of ethylmethane sulfonate. The best mutant for protoplast fusion was selected based on the capabilities of ${\beta}-galactosidase$ production and lactose fermentation. The protoplast fusion using polyethylene glycol and calcium chloride solution led to the fusion frequence of $3{\times}10^{-6}$ and a number of fusants were obtained. Among these fusants, a fusant F-3-19 showed the best results in terms of ethanol tolerance, ${\beta}-galactosidase$ activity and lactose fermentation. The performance of lactose fermentation and ethanol tolerance by this fusant were better than those of K. fragilis. Study on the ethanol tolerance having relation to fatty acid composition and intracellular ethanol concentration revealed that the fusant F-3-19 had a higher unsaturated fatty acids content and accumulated less amount of intracellular ethanol compared with a parent of K. fragilis.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.4
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• pp.439-445
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• 1999

This study is to investigate the mechanism of inhibitory effect of imipramine on the calcium utilization in single cells isolated from canine detrusor. 2 mm thick smooth muscle chops were incubated in 0.12% collagenase solution at $36^{circ}C,$ and aerated with 95% $O_2/5%\;CO_2,$ and then cell suspension was examined. Acetylcholine (ACh) evoked a concentration-dependent contraction of the isolated detrusor cells in normal physiologic salt solution (PSS), and the ACh-induced contraction was significantly inhibited by imipramine. In $Ca^{2+}-free$ PSS, ACh-induced contraction was less than those in normal PSS and it was not affected by the pretreatment with imipramine. $Ca^{2+}-induced$ contraction in $Ca^{2+}-free$ PSS was supressed by imipramine, but addition of A 23187, a calcium ionophore, overcomed the inhibitory effect of imipramine. High potassium-depolarization (40 mM KCl) evoked cell contraction, which was inhibited by imipramine. Caffeine, a releasing agent of the stored $Ca^{2+}$ from sarcoplasmic reticulum, evoked a contraction of the cells that was not blocked by the pretreatment with imipramine. These results suggest that imipramine inhibits the influx of calcium in the detrusor cells through both the receptor-operated- and voltage-gated-calcium channels, but does not affect the release of calcium from intracellular storage site.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.3
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• pp.95-99
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• 2008

Calcium ($Ca^{2+}$) is an intracellular second messenger associated with neuronal plasticity of the central nervous system. The calcium-binding proteins regulate the $Ca^{2+}$-mediated signals in the cytoplasm and buffer the calcium concentration. This study examined temporal changes of three calcium-binding proteins (calretinin, calbindin and parvalbumin) in the medial vestibular nucleus (MVN) during vestibular compensation after unilateral labyrinthectomy (UL) in rats. Rats underwent UL, and the changes in the expression of these proteins at 2, 6, 12, 24, 48, and 72 h were examined by immuno-fluorescence staining. The expression levels of all three proteins increased immediately after UL and returned to the control level by 48 h. However, the level of calretinin showed changes different from the other two proteins, being expressed at significantly higher level in the contralateral MVN than in the ipsilateral MVN 2 h after UL, whereas the other two proteins showed similar expression levels in both the ipsilateral and contralateral MVN. These results suggest that the calcium binding proteins have some protective activity against the increased $Ca^{2+}$ levels in the MVN. In particular, calretinin might be more responsive to neuronal activity than calbindin or parvalbumin.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.4
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• pp.387-397
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• 2016

Neurofibrillary tangles (NFTs) of microtubule-associated protein tau are a pathological hallmark of Alzheimer's disease (AD). Endoplasmic reticulum (ER) stress has been known to be involved in the pathogenesis of AD. However, the exact role of ER stress in tau pathology has not yet been clearly elucidated. In present study, the possible relationship between tau pathology and ER stress was examined in terms of sorcin, which is a calcium binding protein and plays an important role in calcium homeostasis. Our previous yeast two hybrid study showed that sorcin is a novel tau interacting protein. Caspase-3-cleaved tau (T4C3) showed significantly increased tau-sorcin interaction compared to wild type tau (T4). Thapsigargin-induced ER stress and co-expression of constitutively active $GSK3{\beta}$ ($GSK3{\beta}-S9A$) also exhibited significantly increased tau-sorcin interactions. T4C3-expressing cells showed potentiated thapsigargin -induced apoptosis and disruption of intracellular calcium homeostasis compared to T4-expressing cells. Overexpression of sorcin significantly attenuated thapsigargin-induced apoptosis and disruption of calcium homeostasis. In contrary, siRNA-mediated knock-down of sorcin showed significantly increased thapsigargin-induced apoptosis and disruption of calcium homeostasis. These data strongly suggest that sequestration of sorcin by aberrant forms of tau compromises the function of sorcin, such as calcium homeostasis and cellular resistance by ER stress, which may consequently result in the contribution to the progression of AD.

• Archives of Pharmacal Research
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• v.18 no.5
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• pp.295-300
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• 1995

These studies were designed to examine the effects of ginsenosides on glutamate neurotansmission. In primary cultures of rat cerebellar granule cells, ginsenosides (Rb1, Rc did not Rg1, $500\mug/ml$) increased glutamate release which was measured by HPLC. but HPLC, but Re did not shwo an elevation of glutamate release. However, all of these ginsenosides down-regulated N-methyl-D-aspartate (NMDA)-induced glutamate release. Rc strongly increased glutamate release and elevated intracellular clcium concentrations $([Ca_{2+}]_i)$ which was measured by ratio fluorometry with FURA-2AM. These results indicate that ginsenosides have a homeostatic effect on glutamate neurotransmission, and there is a structure-function relationship among the ginsenosides tested.

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.49-49
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• 2001

Sphingosine 1-phosphate is a metabolite of complex sphingolipids that acts as both a second messenger and as a high-affinity ligand for cell surface receptor. Since the possible involvement of sphingosine 1-phosphate has not been investigated in adipocyte, we examined the response of intracellular calcium ([Ca$^{2＋}$]$_{i}$) and intracellular cAMP ([cAMP]$_{i}$ and the effect of sphingosine 1-phosphate on adipocyte function using rat primary adipocyte.(omitted)ted)

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.81-89
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• 1992

Enuresis is a common voiding disorder among children. There are several therapeutic regimens for the disorder available today; behavioral therapies, psychotherapy, bladder training, sleep interruption, hypnosis and drug therapy. Recently, the efficacy of drug therapy has been acknowledged, particularly of antidepressants. Among the tricyclic antidepressants, imipramine is most frequently employed for the treatment of enuresis. Present study was undertaken to investigate the mechanism of imipramine on the contractility of urinary bladder in relation to the calcium modulation using isolated strips of rat detrusor urinae. 1. The electric fileld stimulation-induced contraction was abolished by imipramine, but partially inhibited by atropine. 2. Imipramine reduced the basal tone and diminished the phasic activity of detrusor muscle concentration-dependently, which was similar to that of diltiazem, a calcium channel blocker. 3. Imipramine suppressed the maximal responses and shifted the concentration-response curves of bethanechol and ATP to right. 4. Imipramine inhibited the calcium-induced recovery of tension in calcium-free physiologic salt solution (PSS) with a mode of action similar to that of diltizaem. 5. A23187, a calcium ionophore recovered the basal tone which had been reduced by imipramine in normal PSS. 6. In calcium-free PSS, A23187 could recover the abolished basal tone with the pretreatment of imipramine, but it exerted a partial recovery with the pretreatment of TMB-8, an inhibitor of intracellular calcium release. Based on these results, it is suggested that the inhibitory action of imipramine on the detrusor muscle exerted in part by blockade of the muscarinic and purinergic receptors, and interference with the influx of extracellular calcium, but not with the release of intracellular stored calcium, is involved in its mechanism of action.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.2
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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.

• Molecules and Cells
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• v.25 no.3
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• pp.390-396
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• 2008

Calreticulin (CRT) is one of the major $Ca^{2+}$ binding chaperone proteins of the endoplasmic reticulum (ER) and an unusual luminal ER protein. Postnatally elevated expression of CRT leads to impaired development of the cardiac conductive system and may be responsible for the pathology of complete heart block. In this study, the molecular mechanisms that affect $Ca^{2+}$-dependent signal cascades were investigated using CRT-overexpressing cardiomyocytes. In particular, we asked whether calreticulin plays a critical role in the activation of $Ca^{2+}$-dependent apoptosis. In the cells overexpressing CRT, the intracellular calcium concentration was significantly increased and the activity of PKC and level of SECAR2a mRNA were reduced. Phosphorylation of Akt and ERKs decreased compared to control. In addition the activity of the anti-apoptotic factor, Bcl-2, was decreased and the activities of pro-apoptotic factor, Bax, p53 and caspase 8 were increased, leading to a dramatic augmentation of caspase 3 activity. Our results suggest that enhanced CRT expression in mature cardiomyocytes disrupts intracellular calcium regulation, leading to calcium-dependent apoptosis.

• The Korea Journal of Herbology
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• v.29 no.4
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• pp.83-89
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• 2014

Objectives : The purpose of this study was to investigate effects of Houttuyniae Herba water extract (HC) on calcium release and production of various inflammatory mediators such as nitric oxide (NO), interferon-inducible protein (IP)-10, platelet derived growth factor (PDGF)-BB, keratinocyte-derived chemokine (KC), vascular endothelial growth factor (VEGF), interleukin (IL)-4, and IL-5 in lipopolysaccharide (LPS)-induced RAW 264.7 mouse macrophages. Methods : NO production was measured by Griess reagent assay. Intracellular calcium level was measured with Fluo-4 assay. Levels of cytokines were measured by High-throughput multiplex bead array cytokine assay based on xMAP (multi-analyte profiling beads) technology. Results : HC significantly decreased NO production for 24 hrs incubation at the concentrations of 10, 25, 50, 100, and $200{\mu}/mL$ in LPS-induced RAW 264.7 (P < 0.05). HC significantly decreased production of IP-10, KC, VEGF, and PDGF-BB for 24 hrs incubation at the concentrations of 50, 100, and $200{\mu}/mL$ in LPS-induced RAW 264.7 (P < 0.05). HC also significantly decreased intracellular calcium release for 24 hrs incubation at the concentrations of 25, 50, 100, and $200{\mu}/mL$ in LPS-induced RAW 264.7 (P < 0.05). But HC did not show any significant effect on production of IL-4 and IL-5 in LPS-induced RAW 264.7. Conclusions : The results suggested that HC has anti-inflammatory property related with its inhibition on the production of NO, IP-10, KC, VEGF, and PDGF-BB in LPS-induced macrophages via calcium pathway.