Kunio Ishii
University of Shizuoka
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Featured researches published by Kunio Ishii.
European Journal of Pharmacology | 1997
Naohiro Masumoto; Koichi Nakayama; Akihiro Oyabe; Mayumi Uchino; Kunio Ishii; Kazuo Obara; Yoshiyuki Tanabe
In order to determine whether protein tyrosine kinase mechanisms are involved in pressure-induced contraction, we compared effects of three structurally unrelated tyrosine kinase inhibitors and orthovanadate, a tyrosine phosphatase inhibitor, on the pressure-induced contraction of the posterior cerebral artery isolated from rats. The change in vessel diameter was continuously measured with a width analyzer. Herbimycin A inhibited the pressure-induced contraction, while it only slightly inhibited contractions produced by potassium chloride or 9,11-dideoxy-11alpha,9alpha-epoxymethano prostaglandin F2alpha (U46619). Genistein inhibited not only the pressure-induced contraction but also the U46619-induced one. Tyrphostin 23 significantly attenuated contractions in response to three different stimuli, i.e., pressure, potassium chloride and U46619. Orthovanadate potentiated the pressure-induced contraction. These results suggest that herbimycin A is a specific and potent inhibitor of the pressure-induced contraction and that a protein tyrosine kinase mechanism may play an important role in the genesis of the pressure-induced contraction of the rat cerebral artery.
Life Sciences | 1994
Yoshio Tanaka; Shinzo Hata; Hiromi Ishiro; Kunio Ishii; K. Nakayama
The present study was undertaken to know whether the formation of inositol 1,4,5-trisphosphate (IP3) is increased by quick stretch, a dynamic mechanical stimulus in porcine coronary artery in order to inquiry the possibility that IP3 could mediate Ca2+ release in the stretch-induced contraction. Quick stretching of a helical strip of porcine coronary artery at a rate of 10 cm/sec, the amount of stretch equivalent to 140% of the initial muscle length (= 100%), and the stimulus period of 30 sec with 20-min intervals, produced delayed contraction. Quick stretching increased the content of IP3 about three-fold over the control basal level, which always preceded the contraction. A putative phospholipase C inhibitor, 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (NCDC), abolished the increase in the formation of IP3 and partially inhibited the stretch-induced contraction. The results suggest that quick stretching increases the formation of IP3 through a possible mechanism for activation of phospholipase C, which may lead to release of Ca2+ into myoplasm and to further activation of the contractile elements.
Life Sciences | 1999
Noriko Matsuura; Tomohisa Ishikawa; Shin-ichi Abe; Hironori Yuyama; Fumi Sugino; Kunio Ishii; Koichi Nakayama
Involvement of nitric oxide (NO) in the regulation of insulin secretion from pancreatic beta-cells was investigated by measuring cytosolic Ca2+ concentration ([Ca2+]i) in isolated rat pancreatic beta-cells. At 7.0 mM glucose, L-arginine (0.1 mM) elevated [Ca2+]i in about 50% of the beta-cells examined. The response was partially inhibited by an NO synthase inhibitor, N(G)-monomethyl-L-arginine (L-NMA; 0.1 mM), suggesting that part of the response was mediated by the production of NO from L-arginine. D-Arginine at higher concentrations (3 or 10 mM) also increased [Ca2+]i at 7.0 mM glucose; however, the response was not affected by L-NMA (0.1 mM). Similar [Ca2+]i elevation was produced by NO (10 nM) and sodium nitroprusside (SNP; 10 microM) at 7.0 mM glucose. The SNP-induced increase in [Ca2+]i was abolished by nicardipine (1 microM), suggesting that the [Ca2+]i response is mediated by Ca2+ influx through L-type voltage-operated Ca2+ channels. In the presence of oxyhemoglobin (1 microM), the [Ca2+]i elevation induced by NO (10 nM) was abolished. Neither degradation products of NO, NO2- nor NO3-, caused any changes in [Ca2+]i. 8-Bromo-cyclic GMP (8-Br-cGMP; 3 mM) and atrial natriuretic peptide (0.1 microM) elevated [Ca2+]i at 7.0 mM glucose. We conclude that NO, which is produced from L-arginine in pancreatic islets, facilitates glucose-induced [Ca2+]i increase via the elevation of cGMP in rat pancreatic beta-cells. NO-cGMP system may physiologically regulate insulin secretion from pancreatic beta-cells.
European Journal of Pharmacology | 1995
Yoshio Tanaka; Tohru Nakazawa; Hiromi Ishiro; Michihiro Saito; Hisayuki Uneyama; Seinosuke Iwata; Kunio Ishii; Koichi Nakayama
The effects of neuropeptide Y on isometric tension simultaneously measured with cytosolic Ca2+ concentration ([Ca2+]cyt) and Ca2+ sensitivity of contractile elements were studied in isolated canine basilar arteries. Neuropeptide Y (1-100 nM) increased [Ca2+]cyt and tension in a concentration-dependent and parallel manner, whereas 9,11-dideoxy-11 alpha,9 alpha-epoxymethano prostaglandin F2 alpha (U46619) (10-100 nM), a thromboxane A2 mimetic, produced a large contraction with a small increase in [Ca2+]cyt. Ca2+ channel antagonists such as d-cis-diltiazem (10 mM) abolished both [Ca2+]cyt and tension augmented by neuropeptide Y. In Ca(2+)-free solution containing 0.2 mM EGTA, neuropeptide Y did not change [Ca2+]cyt and tension, whereas U46619 transiently increased both of them. Furthermore, neuropeptide Y apparently did not affect the Ca2+ sensitivity when assessed in the artery permeabilized with Staphylococcus aureus alpha-toxin, whereas U46619 augmented it. These findings suggest that neuropeptide Y-induced contraction in the canine basilar artery is produced mainly by Ca2+ influx through L-type Ca2+ channels.
European Journal of Pharmacology | 1995
Tsutomu Nakahara; Kunio Ishii; Yoshio Tanaka; Koichi Nakayama
The mechanism of the NG-nitro-L-arginine (L-NNA)-induced pressor response was examined in pentobarbital-anesthetized dogs. The pressor effect of L-NNA (50 mg/kg, i.v.) was significantly and equally diminished by pretreatment with either hexamethonium (25 mg/kg, i.v.) or phentolamine (5 mg/kg, i.v.). The intracisternal administration of L-NNA (1 mg/kg), which did not cause changes in cardiovascular parameters when administered systemically, produced a significant pressor response and tachycardia. Furthermore, significant suppression of L-NNA-induced pressor responses was observed after treatment of dogs with captopril (5 mg/kg, i.v.) or a non-peptide angiotensin II receptor antagonist, losartan (10 mg/kg, i.v.), or bilateral occlusion of renal veins. The inhibitory effects of hexamethonium and losartan were additive. These results suggest that, in addition to vasoconstriction due to the inhibition of endothelial nitric oxide production, increased activity of the sympathetic nervous and renin-angiotensin systems contributes significantly to the development of pressor responses produced by the intravenous injection of L-NNA in anesthetized dogs.
Pflügers Archiv: European Journal of Physiology | 2003
Akihiko Kiyoshi; Tomohisa Ishikawa; Ken-ichi Hayashi; Yoshiyuki Iwatsuki; Kunio Ishii; Koichi Nakayama
Journal of Pharmacological Sciences | 2003
Daisuke Chino; Yukiyoshi Fujita; Kunio Ishii; Koichi Nakayama
Archive | 2008
Tsutomu Nakahara; Kunio Ishii
Biological & Pharmaceutical Bulletin | 1997
Tsutomu Nakahara; Kunio Ishii; Yoshio Tanaka; Koichi Nakayama
Biomedical Research-tokyo | 1994
Yoshio Tanaka; Hiromi Ishiro; T. Nakazawa; Maki Saito; Kunio Ishii; K. Nakayama