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989 results on '"Nakajima Toshiaki"'

204. Thiazolidinediones Inhibit Vasoactive Agent-induced [Ca.sup.2+] Mobilization and Cell Proliferation in Vascular Smooth Muscle Cells

Author

ASANO, MICHIKO, OKUDA, YUKICHI, NAKAJIMA, TOSHIAKI, SUZUKI, SEIJI, and YAMASHITA, KAMEJIRO

Subjects
Research, Diabetes research, Diabetes -- Research
Abstract

Thiazolidinediones belongs to a novel group of oral hypoglycemic drugs increases insulin sensitivity and responsiveness of target organs in patients with non-insulin-independent diabetes mellitus, atherosclerosis, and hypertension where insulin resistance [...]

Published
1999

212. Antiarrhythmic effect and its underlying ionic mechanism of 17β-estradiol in cardiac myocytes

Author

Nakajima, Toshiaki, Iwasawa, Kuniaki, Oonuma, Hitoshi, Morita, Toshihiro, Goto, Atsuro, Wang, Yuepeng, and Hazama, Hisanori

Subjects
Cardiotonic Agents, Patch-Clamp Techniques, Calcium Channels, L-Type, Estradiol, Pyridines, Myocardium, Guinea Pigs, Estrogen Antagonists, Isoproterenol, Action Potentials, Heart, In Vitro Techniques, Membrane Potentials, Piperidines, Papers, Androgens, Potassium Channel Blockers, Animals, Female, Calcium Channels, Estrogens, Non-Steroidal, Anti-Arrhythmia Agents
Abstract

1. The effects of oestrogens on action potential and membrane currents were examined in single guinea-pig atrial myocytes. 2. 17Beta-estradiol (3-10 microM) shortened the action potential duration without significant changes in the resting membrane potential. E-4031 (1 microM) markedly prolonged the action potential duration and induced early afterdepolarization, and 17beta-estradiol (10 microM) abolished it. 3. When cells were perfused in isoproterenol-containing solution, action potentials due to abnormal automaticity caused by membrane depolarization developed, and were also inhibited by 17beta-estradiol. 4. Under voltage clamp conditions, the voltage-dependent Ca2+ currents consisted of both T-(I(Ca,T)) and L-type (I(Ca,L)). 17Beta-estradiol reduced I(Ca,L) concentration-dependently, while it (10 microM) suppressed I(Ca,T) only by approximately 10%. 17Beta-estradiol did not affect time courses of I(Ca,L) inactivation, but it shifted the steady-state inactivation curve to more negative potentials. 5. 17Beta-estradiol (10 microM) did not affect the time-dependent K+ current (I(K)), referred to as I(Kr) and I(Ks) and inwardly rectifying K+ current. However, 17beta-estradiol (30 microM) or diethylstilbestrol (10 microM) inhibited K+ currents. 6. DES and ethinylestradiol (EES) also suppressed I(Ca,L), but testosterone and progesterone failed to inhibit I(Ca,L) The potency of the inhibitory effect on I(Ca,L) was DESEES17beta-estradiol. 7. 17Beta-estradiol and DES also inhibited the cyclic AMP-enhanced I(Ca,L), but cyclic GMP in the pipette or pretreatment of L-NAME could not block the effects of oestrogen on I(Ca,L). 8 These results suggest that oestrogen specifically has antiarrhythmic effects, possibly by acting the L-type Ca2+ channels. The antiarrhythmic effects of oestrogens may contribute to the cardioprotective actions of oestrogens.

Published
1999

216. Aerobic degradation of trichloroethylene by a methanotroph, 'Methylocystis' sp. M

Author

Nakajima, Toshiaki, ナカジマ, トシアキ, Nakajima, Toshiaki, and ナカジマ, トシアキ

Abstract

Thesis (Ph.D.)--University of Tsukuba, (A), no. 1042, 1992.3.25, 揮発性有機塩素化合物の一種であるトリクロロエチレンは,機械金属部品の脱脂・洗浄剤としてＩＣ産業などの分野で広い用途がある。一方,本物質が発癌性でありかつ難分解性であることから, 環境汚染物質として大きな社会問題となっている。本研究では,微生物によりトリクロロエチレンを好気的に分解することを試みた。すなわち,トリクロロエチレン高分解能を有する細菌を検索し,その菌学的諸性質,トリクロロエチレンに対する分解特性,分解経路および分解に関与する酵素について検討を加えた。 ..., http://www.tulips.tsukuba.ac.jp/mylimedio/dl/page.do?bookid=100643740&old_bookid=716774

Published
2007

217. Inhibitory effects of ω-3 polyunsaturated fatty acids on receptor-mediated non-selective cation currents in rat A7r5 vascular smooth muscle cells

Author

Asano, Michiko, Nakajima, Toshiaki, Iwasawa, Kuniaki, Hazama, Hisanori, Omata, Masao, Soma, Masaaki, Yamashita, Kamejiro, and Okuda, Yukichi

Subjects
Guanosine 5'-O-(3-Thiotriphosphate), Papers, Fatty Acids, Omega-3, Animals, Receptors, Cell Surface, Ion Channels, Muscle, Smooth, Vascular, Cell Line, Rats
Abstract

1. The effects of omega-3 polyunsaturated fatty acids on receptor-mediated non-selective cation current (Icat) and K+ current were investigated in aortic smooth muscle cells from foetal rat aorta (A7r5 cells). The whole-cell voltage clamp technique was employed. 2. With a K(+)-containing solution, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA, 30 microM) produced an outward current at a holding potential of -40 mV. This response was inhibited by tetraethylammonium (20 mM) or Cs+ in the patch pipette solution, and the reversal potential of the EPA-induced current followed the K+ equilibrium potential in a near Nernstian manner. 3. Under conditions with a Cs(+)-containing pipette solution, both vasopressin and endothelin-1 (100 nM) induced a long-lasting inward current at a holding potential of -60 mV. The reversal potential of these agonist-induced currents was about +0 mV, and was not significantly altered by the replacement of the extracellular or intracellular Cl+ concentration, suggesting that the induced current was a cation-selective current (Icat). 4. La3+ and Cd2+ (1 mM) completely abolished these agonist-induced Icat, but nifedipine (10 microM) failed to inhibit it significantly. 5. omega-3 polyunsaturated fatty acids (3-100 microM), EPA, DHA and docosapentaenoic acids (DPA), inhibited the agonist-induced Icat in a concentration-dependent manner. The potency of the inhibitory effect was EPADHADPA, and the half maximal inhibitory concentration (IC50) of EPA was about 7 microM. 6. Arachidonic and linoleic acids (10, 30 microM) showed a smaller inhibitory effect compared to omega-3 fatty acids. Also, oleic and stearic acids (30 microM) did not show a significant inhibitory effect on Icat. 7. A similar inhibitory action of EPA was observed when Icat was activated by intracellularly applied GTP gamma S in the absence of agonists, suggesting that the site of action of omega-3 fatty acids is not located on the receptor. 8. These results demonstrate that omega-3 polyunsaturated fatty acids can activate a K+ current and also effectively inhibit receptor-mediated non-selective cation currents in rat A7r5 vascular smooth muscle cells. Thus, the data suggest that omega-3 fatty acids may play an important role in the regulation of vascular tone.

Published
1997

227. Cardiac rehabilitation decreases plasma pentraxin 3 in patients with cardiovascular diseases

Author

Fukuda, Taira, primary, Kurano, Miwa, additional, Iida, Haruko, additional, Takano, Haruhito, additional, Tanaka, Tomofumi, additional, Yamamoto, Yumiko, additional, Ikeda, Kenichi, additional, Nagasaki, Mika, additional, Monzen, Koshiro, additional, Uno, Kansei, additional, Kato, Masayoshi, additional, Shiga, Taro, additional, Maemura, Koji, additional, Masuda, Nobuhito, additional, Yamashita, Hiroshi, additional, Hirata, Yasunobu, additional, Nagai, Ryozo, additional, and Nakajima, Toshiaki, additional

Published
2011
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