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Volume 99, Issue 1
Displaying 1-7 of 7 articles from this issue
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Norimichi NAKAHATA1992 Volume 99 Issue 1 Pages 1-11
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSThe signal transduction of prostaglandin E2 (PGE2) and thromboxane A2 (TXA2), cyclooxygenase products of arachidonic acid, was investigated in smooth muscle preparations and 1321N1 human astrocytoma cells. While PGE2 has been known to stimulate (via EP2 receptor) or inhibit (via EP3 receptor) adenylate cyclase, PGE2 activated phosphatidylinositol 4, 5-bisphosphate (PIP2)-specific phospholipase C (PLase C) in non-vascular smooth muscles (via EP1 receptor), resulting in accumulations of inositol trisphosphate (IP3) and diacylglycerol to elicit intracellular Ca2+ mobilization. On the other hand, STA2, a TXA2 receptor analogue, also accumulated IP3 in human astrocytoma cells. [3H]SQ 29548, a TXA2 receptor antagonist, specifically bound to astrocytoma membranes. TXA2-receptor antagonists (ONO NT-126, S-145, SQ29548 and ONO3708) concentration-dependently inhibited PIP2-specific PLase C activation by STA2, and they also inhibited [3H] SQ 29548 binding in human astrocytoma cells. The Ki value of each antagonist in PIP2-specific PLase C inhibition was similar to that in [3H]SQ29548 binding inhibition. In membrane preparations, STA2 activated PIP2-specific PLase C in the presence of GTPγS. Pertussis toxin (IAP) did not affect STA2-induced PLase C activation. The results suggest that stimulation of TXA2 receptors activates PIP2-specific PLase C via an IAP-insensitive G-protein.View full abstractDownload PDF (8869K) -
Satoshi MURAYAMA, Yukio HARA, Ahmmed ALLY, Toshio SUZUKI, Masaji TAMAG ...1992 Volume 99 Issue 1 Pages 13-18
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSSix new quinolones: enoxacin, norfloxacin, ofloxacin, ciprofloxacin, lomefloxacin, and tosufloxacin and eight nonsteroidal anti-inflammatory drugs: fenbufen, flurbiprofen, ketoprofen, pranoprofen, ibuprofen, indomethacin, mefenamic acid and aspirin were tested for their ability to produce a central stimulating effect in mice. At 5 min after the oral administration of one of the nonsteroidal anti-inflammatory drugs, a new quinolone was administered orally. The combination of drugs induced convulsions in a dosedependent manner, and some mice died as a result of the convulsions. The survival time was used as an index to measure the intensity of convulsions induced by the drug combination. The new quinolones in combination with fenbufen at 100 mg/kg produced convulsions in the following order of potencies: enoxacin > lomefloxacin > norfloxacin. In contrast, administration of fenbufen together with ofloxacin, ciprofloxacin, or tosufloxacin up to a dose of 1000 mg/kg caused no convulsions. Four nonsteroidal antiinflammatory drugs combined with enoxacin at 100 mg/kg also caused convulsion dose-dependently. The order of potency in producing convulsion was as follows : fenbufen > flurbiprofen > ketoprofen = pranoprofen. However, no convulsions were produced by treatment of ibuprofen, indomethacin, mefenamic acid or aspirin together with enoxacin. From these results, the important chemical structures of the new quinolones particularly concerned with the appearance of convulsion were discussed.View full abstractDownload PDF (4608K) -
Masaaki YAMAZAKI, Noboru TODA1992 Volume 99 Issue 1 Pages 19-26
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSMechanisms of histamine-induced relaxation in dog mesenteric artery and vein strips were compared. Histamine elicited a concentration-related relaxation in the arterial strips contracted with prostaglandin (PG) F2α; the relaxations induced at 5 × 10-7 M or higher were composed of phasic and tonic patterns. The phasic component of relaxation was inhibited by chlorpheniramine, but not by cimetidine. Combined treatment with the H1 and H2 antagonists abolished the amine-induced relaxation. The tonic component was inhibited by cimetidine. The phasic relaxation was attenuated by removal of the endothelium. Treatment with indomethacin inhibited the phasic component in the strips with endothelium, but did not influence the relaxation after endothelium denudation. Combined treatment with indomethacin and cimetidine, but not chlorpheniramine, abolished the response. On the other hand, histamine produced a concentration-related, tonic relaxation in the mesenteric vein strips. The relaxation was not influenced by indomethacin, endothelium-denudation, and chlorpheniramine, but was abolished by cimetidine. It may be concluded that the phasic relaxation of dog mesenteric arterial strips is mediated mainly by H1 receptors in the endothelium, resulting in the synthesis and release of PGI2. The tonic relaxation appears to be elicited by activation of H2 receptors in smooth muscle. Mesenteric vein relaxations induced by histamine are likely to be mediated solely by H2 receptors in smooth muscle.View full abstractDownload PDF (5780K) -
Daisuke MOCHIZUKI, Sachiko SUGIYAMA, Yoshiki SHINODA1992 Volume 99 Issue 1 Pages 27-35
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSEffects of oxiracetam on cholinergic neurons were investigated by biochemical methods. 1) Oxiracetam did not inhibit 3H-QNB binding in the cerebral cortex and hippocampus. 2) In the 3H-QNB binding study, oxiracetam did not change the inhibition-concentration curve for the muscarinic agonist carbachol and had no effect on GppNHp-induced inhibition of oxotremorine binding. 3) Oxiracetam (10 ?? 100 μM) enhanced K+-induced ACh release from slices of rat hippocampus. 4) In the in vitro perfusion studies, oxiracetam (10 ?? 10 μM), but not aniracetam and piracetam, enhanced cholineacetyltransferase (ChAT) activity in the hippocampal slices. 5) Repeated administration of oxiracetam (100 or 500 mg/kg, p.o., once daily) to old rats significantly enhanced ChAT activities in the cerebral cortex, hippocampus and striatum, while it did not influence the Bmax and Kd for 3H-QNB binding in the hippocampus. 6) Oxiracetam did not affect the acetylcholinesterase activity in mouce brain homogenate. These results suggest that oxiracetam enhances precholinergic functions.View full abstractDownload PDF (7514K) -
Mitsuaki SAKASHITA, Sadao NAKAYAMA, Masaki KITAHARA, Nobutomo TSURUZOE ...1992 Volume 99 Issue 1 Pages 37-43
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSThe anti-atherogenic effect of NIP-200 (3, 5-dimethyl-4, 6-diphenyl-tetrahydro-2H-1, 3, 5-thiadiazine-2thione) was studied in. experimental models of 1 % cholesterol diet (HCD) -fed rabbits. Interference with growth of the animals did not occur in NIP-200-treated rabbits. NIP-200 had no effect on plasma total cholesterol (TC), triglyceride, free cholesterol and phospholipid during the entire experimental period. However, NIP-200 increased high density lipoprotein-cholesterol (HDL-C) at 1, 2, 4 and 6 weeks, although the average rate of increase was not statistically significant. Percentage surface areas of atherosclerotic lesions on the aorta in NIP-200-treated rabbits (26 ± 6%) was significantly lower than those in HCD-fed rabbits (48 ± 8%) (P < 0.05). Histological studies indicated that NIP-200 prevented intimal thickening, proliferation of elastic fibers and fatty necrosis. Thus, NIP-200 prevented the progression of atherosclerosis without affecting the serum TC. The above results suggest that the improvement of lipoprotein metabolism on the arterial wall and the prevention of migration and proliferation of arterial smooth muscle cells may also be important factors in the progression of atherosclerosis.View full abstractDownload PDF (6025K) -
Toshio SUZUKI, Yukio HARA, Masaji TAMAGAWA, Kazushi KAKIZAKI, Satoshi ...1992 Volume 99 Issue 1 Pages 45-54
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSA combination of fenbufen, a non-steroidal anti-inflammatory drug and the new quinolone produces a central stimulating action. To confirm the action, we used 6 kinds of new quinolones: enoxacin, norfloxacin, ofloxacin, ciprofloxacin, lomefloxacin and tosufloxacin in this experiment. The convulsive effects of these drugs were tested on the EEG recorded from the neocortex and subcortical regions of the rabbits. Animals treated with fenbufen (50 ?? 200 mg/kg, p.o.) tended to have a high amplitude slow wave in their EEG. Rabbits treated with the new quinolones at the dose of 100 mg/kg, p.o., with the exception of tosufloxacin, also tended to show a high amplitude slow wave in their EEG. Each new quinolone given 30 min after fenbufen (50 mg/kg, p.o.) elicited characteristic spikes on the EEG. Then, high-frequency-spikes and epileptiform seizure waves appeared for a long experimental period with this combination. The combination of fenbufen and tosufloxacin (100 ?? 400 mg/kg, p.o.) caused no changes in EEG and behavior. The spike and epileptiform wave could be suppressed only temporarily with diazepam (1 ?? 4mg/kg, i.v.). These results suggest that combined use of fenbufen and one of the new quinolones, except for tosufloxacin, produces the seizure. Not only GABA but also several other mechanisms in the central nervous system may be involved in the convulsion.View full abstractDownload PDF (7218K) -
Koji ITO, Satuki NAMIKAWA, Kumeji TAKEUCHI1992 Volume 99 Issue 1 Pages 55-62
Published: 1992
Released on J-STAGE: February 13, 2007
JOURNAL FREE ACCESSEffect of Glyteer (GL) on edema and epidermal hyperplasia in mouse ear by 12-o-tetradecanoylphorbol-13-acetate (TPA) were investigated by its topical application; and the effects were compared with those of betamethasone 17-valerate (BV), indomethacin (IM) and cyclosporin (CS). GL significantly inhibited the edema in mouse ear at 6 hr after TPA treatment. The inhibitory activity of GL on the edema had the same potency as those of BV, IM and CS. Furthermore, GL inhibited the epidermal weight and its protein amount on the hyperplastic response in mouse ear at 3 days after TPA treatment, and the inhibitory activity of GL was also confirmed by the pathologic findings. The mode of the inhibitory action of GL was the same as those of BV and CS, but not that of IM. From those results, it is suggested that GL possesses a potent therapeutic effect for psoriasis.View full abstractDownload PDF (7852K)
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