• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.97-99
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• 1996

Intracellular gradients of the free calcium concentration are thought to be critical for the localization of functional responses within a cell. The mechanism of mechanotransduction may be associated with the localized accumulation of calcium stores for shear stress-exposed endothelial cells. The distribution of the calcium stores and the formation of the stress fibers were investigated by the indirect double immunofluorescent staining method with the calreticulin antibody and rhodamine phalloidin under flow condition. The shear stress of steady flow reorganized the cytoskeleton structure including the bundling and translocation to focal contacts. The calcium stores translocated from the cytoplasm to the focal contacting area. Consequently. accumulation of the calcium stores may participate in the shear stress-induced cytoskeleton organization of endothelial cells.

• Toxicological Research
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• 제18권4호
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• pp.355-362
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• 2002

Pathophysiological elevation of intracellular calcium concentration ($[Ca^{2+}]_1$) in the neuron has been considered as an important responsible factor in the neuronal cell damages. However the mechanism of increase of $[Ca^{2+}]_1$ and the relationship between $[Ca^{2+}]_1$ level and cytotocixity have not been fully demonstrated. In the present study, real-time alteration of $[Ca^{2+}]_1$and cellular response (cell damages) in the pheochromocytoma cells (PC12) stimulated by glutamate were investigated. Glutamate dose dependently decreased cell viability determined propidium iodide fluorescence method and morphology change. Conversely related with cell damages, glutamate dose dependently increased the level of［Ca$^{2+}$］$_{i}$ . To investigate the mechanism of glutamate-induced increase of $[Ca^{2+}]_1$,$[Ca^{2+}]_1$, was first measured in the cell cultured in calcium free media and in the presence of dantrolene, an inhibitor of calcium release from ryanodine receptor located in endoplasmic reticulum (ER). Similar to the increase$[Ca^{2+}]_1$ in the calcium-containing media, glutamate dose dependently increased $[Ca^{2+}]_1$ in the cell cultured in free calcium media. However pretreatment (2 hr) with 20~50 $\mu\textrm{M}$ dantrolene substantial lowered glutamate-induced increase of $[Ca^{2+}]_1$, suggesting that release of calcium from ER may be major sourse of increase of $[Ca^{2+}]_1$ in PC12 cells. Dantrolene-induced inhibition of $[Ca^{2+}]_1$ resulted in recovery of cytotoxicity by glutamate. Relevance of N-methy-D-aspartate (NMDA) receptor, a type of glutamte receptor on glutamate-induced incense of $[Ca^{2+}]_1$,$[Ca^{2+}]_1$ was also determined in the cells pretreated (2 hr) with NMDA receptor antagonist MK-80l. Glutamate-induced increase of $[Ca^{2+}]_1$ was reduced by MK-801 dose dependently. Furthermore, glutamate-induced cytotoxicity was also prevented by MK-80l. These results demonstrate that glutamte increase $[Ca^{2+}]_1$ dose dependently and thereby cause cytotoxicity. The increase of $[Ca^{2+}]_1$ may release from ER, especially through ryanodine receptor and/or through NMDA receptor Alteration of calcium homeostasis through disturbance of ER system and/or calcium influx through NMDA receptor could contribute glutamate-induced cell damages.s.

• 약학회지
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• 제43권6호
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• pp.809-817
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• 1999

The effect of 2-(4-cyanophenyl)amino-1,4-naphthalenedione-3-pyridinium perchlorate (PQ5) on pla-telet aggregation and its action mechanisms were investigated with rat platelet. PQ5 inhibited the platelet aggregation induced by collagen ($6{\;}{\mu\textrm{g}}/ml$), thrombin (0.4 U/ml) and A23187 ($3{\mu}M$) in concentration-dependent manner with $IC_{50}$ values of 5.50, 25.89 and $37.12{\;}{\mu}M$, respectively. PQ5 also significantly reduced the thromboxane $A_2$ (TXA2) formation in a concentration dependent manner. The collagen-induced arachidonic acid (AA) release in [-3H]-AA incorporated platelet, an indication of the phospholipase $A_2$ activity, was decreased by PQ5 pretreatment PQ5 significantly inhibited the activity of thormboxane synthase only at high concentration ($100{\mu}M$), but did not affect the cyclooxygenase activity at all. Collagen-induced ATP release was significantly reduced by PQ5. Calcium-induced platelet aggregation experiment suggests that the elevation of intracellular free $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) by collagen stimulation is decreased by the pretreatment of PQ5, which is due to the inhibition of calcium release from intracellular store and influx from outside of the cell. PQ5 did not showed the effect of anticoagulation as prothrombin time (PT) or activated partial thromboplastin time (APTT). Form these results, it is suggested that PQ5 exerts its antiplatelet activity through the inhibition of the intracellular $Ca^{2+}$ mobilization and the decrease of the $TXA_2$ synthesis.

• The Korean Journal of Physiology and Pharmacology
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• 제9권1호
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• pp.55-62
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• 2005

Very little research has been carried out on safflower seed for the prevention and treatment of the bone deficiency diseases, including osteoporosis, which are supported by scientific evidences. In the present study, $3{\mu}l$ of 0.1% dried crude extract or $2{\mu}l$ of 0.1% dried aqueous fraction were shown to significantly accelerate the rate of differentiation of osteoblast. Also, the crude extract and aqueous fraction increased the $[Ca^{2+}]_i$ of the cultured osteoblast cells: $3{\mu}l$ of 0.1% dried crude extract and $2{\mu}l$ of 0.1% dried aqueous fraction significantly increased the $[Ca^{2+}]_i$ of the cultured osteoblast cells ($8{\times}10^{-4}$) to the extent that it deserves a considerable attention. Furthermore, the crude extract and aqueous fraction increased the $[Ca^{2+}]_i$ of the cultured osteoblast cells, and $300{\mu}M$ $Cd^{2+}$, specific calcium channel blocker, completely blocked the increase. Therefore, the increased $[Ca^{2+}]_i$ of the cultured osteoblast cells by safflower seed component continued to activate calcium channel.

• The Korean Journal of Physiology and Pharmacology
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• 제17권1호
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• pp.1-8
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• 2013

Understanding the cellular and molecular mechanisms involved in the development and progression of pulmonary hypertension (PH) remains imperative if we are to successfully improve the quality of life and life span of patients with the disease. A whole plethora of mechanisms are associated with the development and progression of PH. Such complexity makes it difficult to isolate one particular pathway to target clinically. Changes in intracellular free calcium concentration, the most common intracellular second messenger, can have significant impact in defining the pathogenic mechanisms leading to its development and persistence. Signaling pathways leading to the elevation of $[Ca^{2+}]_{cyt}$ contribute to pulmonary vasoconstriction, excessive proliferation of smooth muscle cells and ultimately pulmonary vascular remodeling. This current review serves to summarize the some of the most recent advances in the regulation of calcium during pulmonary hypertension.

• Restorative Dentistry and Endodontics
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• 제24권3호
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• pp.437-446
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• 1999

Porphyromonas endodontalis(P. endodontalis) is one of the important causative bacteria of pulpal and periapical disease. P. endodontalis has lipopolysaccharide(LPS) and it plays a major role in stimulating the synthesis and release of cytokines from immune cells and prostaglandin $E_2$ from host cells. The purpose of this study is to prepare LPS from P. endodontalis and to evaluate the effect of LPS on membrane permeability of fibroblast. P. endodontalis ATCC 35406 was cultured in anaerobic condition, and LPS was extracted. LPS was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Human periodontal ligament cell, colon fibroblast(CCD-18Co, KCLB 21459) and skin fibroblast(Detroit 551, KCLB 10110) were perfused with 0.01% P. endodontalis LPS solution, high concentration of $K^+$ solution and $Ca^{2+}$-free solution, $Ca^{2+}$ concentration ratio was measured by microfluorometry. 1. Intracellular $Ca^{2+}$ concentration was not changed in human periodontal fibroblast and skin fibroblast(Detroit 551) stimulated by P. endodontalis LPS. 2. Intracellular $Ca^{2+}$ concentration was increased in colon fibroblast(CCD-18Co) stimulated by P. endodontalis LPS. 3. Colon fibroblast(CCD-18Co) has voltage dependent $Ca^{2+}$ channel activated by high concentration of $K^+$ solution. 4. P. endodontalis LPS has no effect on the increase of intracellular $Ca^{2+}$ concentration during perfusion of $Ca^{2+}$-free solution.

• 미생물학회지
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• 제31권1호
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• pp.79-84
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• 1993

Infection of Chinook Salmon Embryo (CHSE) cells with IPNV resulted in a significant decrease in intracellular free calcium concentration ([$Ca^{2+}$]i) compared to mock-infected cells. The degree of the decrease in [Ca$^{2+}$]i was dependent on the amount of input virus, and treatment of IPNV-infected CHSE cells with metabolic inhibitors such as cyloheximide cordycepin partially reversed the decrease in [$Ca^{2+}$]i in IPNV-infected cells. Inactiation of PINV with UV also abolished IPNV-induced decrease in [$Ca^{2+}$]i. These data suggest an active role of IPNV in the decrease of [Ca$^{2+}$]i in the infected CHSE cells. The importance of the decrease in [$Ca^{2}$i] could be supported by the finding that the production of IPNV plaques increased in the cells treated with verapamil, a calcium influex blocker, and by lowering the concentration of extracellular calcium. Decreased production of IPNV plaques was observed by elevating the extracellular calcium. Thus, it is suggested that IPNV induced a decreased in [$Ca^{2+}$]i and the decrease in [$Ca^{2+}$]i may plan an importat role in efficient replication of IPNV.ation of IPNV.

• Journal of Korean Neurosurgical Society
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• 제45권4호
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• pp.231-235
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• 2009

Objective : While many factors contribute to aging, changes in calcium homeostasis and calcium related neuronal processes are likely to be important. High intracellular calcium is toxic to cells and alterations in calcium homeostasis are associated with changes in calcium-binding proteins, which confine free $Ca^{2+}$. We therefore assayed the expression of the calcium binding proteins calretinin and calbindin in the central auditory nervous system of rats. Methods : Using antibodies to calretinin and calbindin, we assayed their expression in the cochlear nucleus, superior olivary nucleus, inferior colliculus, medial geniculate body and auditory cortex of young (4 months old) and aged (24 months old) rats. Results : Calretinin and calbindin staining intensity in neurons of the cochlear nucleus was significantly higher in aged than in young rats (p<0.05) The number and staining intensity of calretinin-positive neurons in the inferior colliculus, and of calbindin-positive neurons in the superior olivary nucleus were greater in aged than in young rats (p<0.05). Conclusion : These results suggest that auditory processing is altered during aging, which may be due to increased intracellular $Ca^{2+}$ concentration, consequently leading to increased immunoreactivity toward calcium-binding proteins.

• Journal of Photoscience
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• 제6권4호
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• pp.187-191
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• 1999

Using fluorescent probe fura-2 acetoxymethyl ester, we studied effects of N-Methyl-D-aspartate (NMDA) on free intracellular $Ca^{2+}$ concentration ([$Ca^{2+}$]$_{i}$) and interaction of ethanol with NMDA-mediated response in freshly dissociated brain cells from newborn rats. Twenty five micromolar NMDA significantly increased ($Ca^{2+}$), and this increasing effect could be prevented or reversed by the NMDA antagonists $Mg^{2}$(1.0 mM) and 2-amino-5-phosphonovalerate (AP5, 100 ${\mu}$M). Ethanol at concentrations from 2.5 to 100 mM inhibited NMDA-mediated calcium current in a concentration-dependent manner. Maximal inhibition of NMDA-mediated calcium current by ethanol was 82% at 50 mM. The ethanol inhibition at 100 mM was not significantly different from the inhibition at 50 mM.

• The Korean Journal of Physiology and Pharmacology
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• 제1권5호
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• pp.565-572
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• 1997

In the freshly isolated rat nephron, the effect of endothelin-1, -2 and -3 (ET-1, -2 and -3) on cytosolic free calcium concentration ($[Ca^{2+}]_i$) was determined using the fluorescent indicator Fura-2/AM. $[Ca^{2+}]_i$ increase was investigated in 9 parts of the single nephron including glomerulus (Glm), $S_1,\;S_2,\;S_3$, cortical and medullary thick ascending limb and cortical (CCT) and outer medullary collecting tubule (OMCT). Endothelins increased $[Ca^{2+}]_i$ in Glm (ET-1; $127{\pm}17%$, ET-2; $93{\pm}5%$, ET-3; $169{\pm}17%$), CCT (ET-1; $30{\pm}6%$, ET-2; $38{\pm}19%$, ET-3; $158{\pm}18%$) and OMCT (ET-1; $197{\pm}11%$, ET-2; $195{\pm}11%$, ET-3; $215{\pm}37%$) at 10-7 M. In OMCT, ET-1 and ET-2 increased $[Ca^{2+}]_i$ in a dose-dependent manner ($10^{-10}{\sim}10^{-6}$ M). To the contrary, ET-3-induced $[Ca^{2+}]_i$ rise was begun from $10^{-12}$ M. BQ-123Na, an antagonist of ETA receptor, at $10^{-4}$ M inhibited about 30% of $[Ca^{2+}]_i$ rise induced by ET-1 and -3. Binding experiments using $[^{125}I]ET-3$ showed the existence of $ET_B$ receptor in OMCT. This binding was replaced by ET-1, ET-2 or ET-3 by the almost same degree but not by angiotensin II or vasopressin.