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Volume 107 (1996)
- Issue 6 Pages 259-
- Issue 5 Pages 213-
- Issue 4 Pages 173-
- Issue 3 Pages 97-
- Issue 2 Pages 47-
- Issue 1 Pages 1-
Volume 107, Issue 5
Displaying 1-4 of 4 articles from this issue
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Hiroyasu SATOH, Hideaki SADA, Noritsugu TOHSE, Koki SHIGENOBU1996 Volume 107 Issue 5 Pages 213-223
Published: 1996
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSElectrical properties of the cardiac muscles drastically change with development. The changes in the current density of ionic currents of cardiomyocytes are inconsistent among species. In cultured embryonic chick ventricular myocytes, the developmental changes in the fast Na+ channel properties (3 to 17-day-old) are reviewed. The sensitivity to TTX, with a KD as high as 2 nM, remains unchanged. The limiting conductance (GNa) increased by 8-10-fold. The activation kinetics such as the steady-state activation (m∞) and time constant of activation (τm) remain unchanged. The voltage-dependence of inactivation kinetics such as the steady state inactivation (h∞) and time constant (τh) shift in the hyperpolarizing direction. The window conductance tends to be reduced. On the other hand, the L-type Ca2+ channel is important during the development of rat heart, and also the fe-type current (dihydropyridine-resistant) is important in the fetal stage. In chick embryo cardiomyocytes, the L-type channel exhibits long-lasting opening behavior. The behavior is gradually abolished during development. cAMP-dependent protein kinase enhances the Ca2+ channel current on and after the late fetal/embryonic stage. cGMP-dependent protein kinase markedly inhibits the Ca2+ channel current in the fetal/embryonic stage, compared with adult heart. These changes would play an important role for cardiac functions during development.View full abstractDownload PDF (8812K) -
Teiko TOYOGUCHI, Yoshito NAKAGAWA1996 Volume 107 Issue 5 Pages 225-235
Published: 1996
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSVancomycin hydrochloride (VCM) has an antibacterial action against Gram positive bacteria, e.g., Methicillin-resistant Staphylococcus aureus (MRSA). In the clinical situation, there are patients with serious infections, being infected with not only MRSA, but also with Gram negative bacteria like Pseudomonas aeruginosa. Because VCM has the adverse reaction of nephrotoxicity, we are apprehensive about using VCM with other antibiotics, which might increase this problem. Therefore, the nephrotoxic effects and pharmacokinetics of VCM were examined in rabbits and compared with those in rabbits administered with VCM and other antibiotics. Responses indicating nephrotoxicity such as increases of serum creatinine concentration and BUN and morphological changes of the kidney were induced by the single injection of VCM at 300 mg/kg, i.v. In contrast, no abnormality of clinical data and morphological alteration were observed in the groups injected with VCM and imipenem (IPM)-cilastatin sodium (CS), flomoxef sodium (FMOX) or fosfomycin sodium (FOM). This was not true for groups injected with VCM and ceftazidime, cefpimizole sodium (CPIZ) or cefoperazone sodium. Clearance of VCM increased obviously in the groups injected with VCM and IPM-CS, FMOX or FOM, but decreased in those given VCM and CPIZ. Since the renal concentrations of VCM in the groups that were administered VCM with IPM-CS, FMOX or FOM were lower than that in the control group, IPM-CS, FMOX and FOM may decrease the nephrotoxicity of VCM by inhibiting its uptake into the kidney.View full abstractDownload PDF (9027K) -
Takeshi MUSHIROI, Rika SHIBAHARA, Masaru TAMURA, Takako SHIMIZU, Yoshi ...1996 Volume 107 Issue 5 Pages 237-245
Published: 1996
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSEffects of a novel TRH analog, montirelin hydrate (NS-3), on the coma caused by head concussion and narcosis induced by pentobarbital were compared with those of TRH in mice. Head concussion caused a behavioral comatose state with loss of the righting reflex and spontaneous motor activity. NS-3 shortened the latent periods to the recovery of the righting reflex (0.03-0.1 mg /kg, i.v.) and spontaneous motor activity (0.1 mg/kg, i.v.) following the head concussion. In the case of TRH, higher doses were needed to induce such effects. NS-3 (0.1-0.3 mg/kg, i.v.) reversed the pentobarbital-induced narcosis in a dose-dependent manner. A similar effect was elicited by 30 to 100-fold higher doses of TRH than NS-3. The analeptic effect of NS-3 in the pentobarbital-narcotized mice was antagonized by SCH23390, a dopamine D1 antagonist or by the combined treatment with prazosin and scopolamine, while neither prazosin nor scopolamine alone antagonized the analeptic effect of NS-3. Taken together with the finding that NS-3 did not bind to dopamine, adrenaline or muscarine receptors, it is suggested that NS-3 may restore the disturbance of consciousness by activating the brain dopamine, noradrenaline and acetylcholine neurons without stimulating these receptors directly.View full abstractDownload PDF (7717K) -
Takashi FUTAMURA, Yoshitaka OHASHI, Kazuhiro YANO, Yukiko TAKAHASHI, K ...1996 Volume 107 Issue 5 Pages 247-253
Published: 1996
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSThe affinities of mosapramine hydrochloride, an iminodibenzyl antipsychotic drug, for dopamine receptor subtypes were determined by human dopamine D2, D3 and D4 receptors expressed in several cell lines and compared with those of other neuroleptics. Tritiated spiperone bound to the membrane of transfected cells in a saturable manner, and the Kd values for dopamine D2, D3 and D4 receptors were 0.021, 0.12 and 0.10 nM, respectively. Mosapramine showed the highest affinities for these receptor subtypes among the antipsychotics tested. The ratio of Ki values between D2 and D3 (D2 Ki/D3 Ki ratio) in mosapramine was higher than that of haloperidol, indicating that the effects of mosapramine on D3 receptors were more potent than those of haloperidol. On the other hand, clozapine, risperidone and raclopride had higher affinity to D4, D2 and D3 subtypes, respectively. The affinities of mosapramine for D4 receptors was 8 times higher than that of clozapine, and the affinity for D3 receptors was 40 times higher than that of raclopride. These results suggest that the effect on D3 receptors may underlie at least a portion of mosapramine's atypical clinical profile.View full abstractDownload PDF (4526K)
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