巻号一覧
29 巻 (2004)
- 6 号 p. 324-
- 5 号 p. 250-
- 4 号 p. 194-
- 3 号 p. 140-
- 2 号 p. 80-
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29 巻, 3 号
選択された号の論文の7件中1～7を表示しています
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眞鍋 健一, 岡田 泰伸2004 年 29 巻 3 号 p. 140-147
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーCell volume regulation under osmotic stress is one of the important cell functions to maintain cell homeostasis. Absorptive intestinal epithelial cells are obliged to swell in association with active absorption of nutrients, whereas secretory cells in the intestinal crypt exhibit shrinkage due to Na+ and H2O secretion driven by active Cl- secretion. After osmotic swelling and shrinkage, intestinal epithelial cells undergo a regulatory volume decrease (RVD) or a regulatory volume increase (RVI), respectively, to restore their original volume. In human epithelial Intestine 407 cells, we demonstrated that the RVD is accomplished by parallel activation of Ca2+-activated K+ channel (IK1) and volume-sensitive outwardly rectifying Cl- channel (VSOR). Small intestinal and colonic epithelial cells have been reported to respond with shrinkage to secretagogue stimulation. We utilized a human colonic epithelial cell line, T84, as a model to clarify the ion transport mechanisms of volume responses to secretagogue situmulation. T84 cells exhibited shrinkage, called a secretory volume decrease (SVD), after stimulation with carbachol (CCh), and they thereafter restored their original volume even during CCh stimulation. Our data showed that CCh-induced SVD is induced by Cl- secretion via Ca2+-activated Cl- channels, and, on the other hand, the succeeding RVI is by NaCl uptake via Na+-K+-2Cl- cotransporters (NKCC). These findings indicate that when intestinal cells are faced with osmotic stress, which is inevitably coupled to active absorption and secretion, they can regulate their volume by activating ion channels and/or transporters.抄録全体を表示PDF形式でダウンロード (1137K) -
佐々木 成2004 年 29 巻 3 号 p. 148-153
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーWater and solutes transport in epithelial tissues is an important mechanism for maintenance of the homeostasis of internal environment; volume and composition of extracellular fluid. Molecular technologies and advancement of the genome projects have identified plenty of membrane proteins that mediate epithelial transport. Membrane transport proteins can be classified into channel, solute carrier, ABC transporter, and pump. Each of the categories includes many families; for example, solute carrier consists of 43 families and 298 genes in human. Reflecting the importance of transport proteins, many hereditary diseases are proved to be due to gene mutations of transport proteins. Cross talk between clinical information and basic cell molecular biology data of these hereditary diseases will further advance our knowledge of transport proteins and their diseases.抄録全体を表示PDF形式でダウンロード (773K) -
長井 孝紀, 田中 滋康, 高田 真理2004 年 29 巻 3 号 p. 154-160
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーAmphibians regulate the osmotic and ionic composition of their body fluids by water and ion transport across their skin. When dehydrated, desert toads press down the pelvic region of ventral skin on moist surfaces to achieve maximal water absorption. Aquaporins (AQP) are trans-membrane proteins permeable to water. We cloned three isoforms of AQP (AQP-h1, -h2, -h3) in tissues of tree frogs. AQP-h3 was abundantly expressed in the pelvic region of ventral skin, facilitating water absorption across the skin. Antibodies to AQP-h3 labeled the cell membrane of the granulosum cells in the skin. AQP-h3 was progressively expressed during metamorphosis of larval frogs. Expression of AQP-h3 was facilitated by and diuretic hormone, argine vasotocin. Collectively, AQP-h3 is a molecule to play a positive role in water absorption across the amphibian skin. In bullfrogs short circuit current across the skin was suppressed by amiloride, a blocker for epithelial Na+ channel (ENaC), showing that transport of sodium ions occurs through ENaC. Na+ transport increased in parallel with metamorphosis of the tadpole. In cultured skins of the tadpole Na+ transport was facilitated by aldosterone, but counteracted by prolactin. Such counteraction seemed to be removed by thyroid hormone (T3) during metamorphosis to adapt a terrestrial environment.抄録全体を表示PDF形式でダウンロード (4223K) -
新里 直美, 丸中 良典2004 年 29 巻 3 号 p. 161-168
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーTo sense an environmental change such as hypotonic shock is a crucial function for cells to adjust to a new environment. Na+ reabsorption in the kidney is finely regulated to maintain body Na+ content, blood pressure, extracellular fluid volume (ECF) and is stimulated by aldosterone, vasopression and extracellular hypotonicity to maintain normal plasma osmolality. On the other hand, hypotonic shock causes drastic cell volume changes; initial cell swelling followed by regulatory volume decrease (RVD). The mechanism of RVD is well understood as K+/Cl-release through volume-sensitive Cl-and K+ channels and a decrease in cytosolic Cl-concentration is associated with the RVD. In this review, we focus our study on a possible role of cytosolic Cl-for sensing extracellular hypotonicity by modulating enzyme activities to regulate tyrosine phosphorylation and suggest the possibility that ion channels and ion transporters function as regulators of signal transduction for extracellular stimuli in addition to the contribution to transepithelial ion transporter.抄録全体を表示PDF形式でダウンロード (1094K) -
大場 哲彦, 渡名喜 力, 大木 和夫2004 年 29 巻 3 号 p. 169-179
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーLaurdan, one of the environment-sensitive fluorescent probes, is useful for monitoring membrane fluidity and is widely used for spectroscopic and imaging applications. In the imaging applications, the generalized polarization parameter (GP), defined by two fluorescent intensities at characteristic wavelengths, is used as a measure of membrane fluidity and polarity. However, time-resolved fluorescent spectra of laurdan revealed that the three excited states concern with the emission spectra. We have measured the steady-state fluorescence spectra and the fluorescence anisotropy of laurdan, prodan and NBD-PE in the DPPC and DLPC bilayers at various temperatures. The spectral dependence on the excitation wavelength is interpreted as the red edge effects that are related to the existence of excited-state distribution of fluorophores on their interaction energy with the environment and the slow dielectric relaxation of this environment. The emission peak of laurdan in the liquid-crystalline phase is independent of the red edge excitation, while prodan and NBD-PE show significant red edge effects. This results strongly suggest that laurdan changes its electronic excited state by the specific interaction with a few water molecules in the bilayers and that in addition the non-specific solvent relaxation causes further spectral shifts in the case of prodan in the bilayers and laurdan in the micella. A new three state model for the absorption and emission of laurdan is proposed. The availability and limitation of the GP method are disscussed.抄録全体を表示PDF形式でダウンロード (1265K) -
Kazuho Nakamura, Hui-yuan Liu, Kanji Matsumoto2004 年 29 巻 3 号 p. 180-187
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーIn order to clarify the effect of electric double layer overlapping in the pore of microporous membrane on the measurements of streaming potential (SP) and the apparent zeta potential, ζobs, of the pore surface, the mixed cellulose ester microporous membranes having different pore sizes ranging from 0.025 to 0.8 μ m were used. The dependence of SP on KCl concentration was measured by the continuous measuring method of SP over the wide range of KCl concentration. Both the SP and the ζ obs estimated from the measured SP had the maximum negative value at a certain value of KCl concentration, which depended on the pore size. The ζ obs obtained from the different pore sizes did not coincide with each other even at the higher κγ, which is the ratio of pore radius, γ, to Debye length, κ-1, where the electric double layer overlapping was assumed to be negligible. However, it was demonstrated that the relationship between SP and KCl concentration could be evaluated from the theoretical calculation by using the fitting parameters of surface charge density and pore size. The calculated pore size of membrane tested was the same order of nominal one.抄録全体を表示PDF形式でダウンロード (880K) -
森 健二郎2004 年 29 巻 3 号 p. 188-191
発行日: 2004/05/01
公開日: 2011/03/04
ジャーナル フリーCheclear O-157 is the immunochromatography test kit which is developed for easy and rapid detection of E.coli O-157 in food. Detection limited of E.coliO-157 by this method was 5 × 104cells/mL. Compare to the result of culture method (official method), data of Checlear O-157 correspond with culture method (official method). But Checlear O-157 showed cross reaction with some strains (Citrobacter freundii, Salmonella urbana, Bacillus cereus) other than E.coli. Considering those results, Checlear O-157 will be useful in preliminary screening of E.coli O157 in food.抄録全体を表示PDF形式でダウンロード (714K)
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