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Volume 112, Issue 4
Displaying 1-6 of 6 articles from this issue
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Masashi AKIYAMA, Takahiro MORIYA, Shigenobu SHIBATA1998 Volume 112 Issue 4 Pages 243-250
Published: 1998
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSCircadian rhythm is an endogenous rhythm that persists in constant conditions with a period of nearly but not identical to 24 hr. Under natural conditions, the circadian clock is precisely entrained to the daily (24 hr) cycle, because environmental stimulus (especially light) induces a phase shift of the clock. In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus has been shown to be the primary pacemaker that drives daily rhythms of behavioral and physiological activity. Photic information is conveyed. from the retina to the SCN directly by the retinohypothalamic tract (RHT) and indirectly by the geniculohypothalamic tract (GHT). The transmitter of the RHT is glutamate, while the GHT is GABA and neuropeptide Y. Serotonergic innervation from the median raphe and melatonin from the pineal body are likely to provide non-photic information to the SCN. Single gene mutations that dramatically alter circadian phenotype were found in the hamster (tau) and mouse (clock). Moreover, the homologous genes of the Drosophila clock gene, per, were found in mammals and the homologue of the mammalian clock was found in Drosophila. These data suggest that the some constitutes of the biological clock may be conserved between Drosophila and mammals, and a transcription-translation feedback loop involving some clock gene products may be a oscillator itself.View full abstractDownload PDF (8316K) -
Katsuyuki MIURA, Motomu MINAMIYAMA1998 Volume 112 Issue 4 Pages 251-256
Published: 1998
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSA number of neurohumoral factors participate in the regulation of renal hemodynamics. Several methods have been developed to study directly the regulation of renal microcirculation. Here, we introduce an in vivo method to visualize renal microcirculation by using hydronephrotic rat kidney, a unique method originally developed by Steinhausen et al. More than 10 weeks after unilateral ureteral ligation in rats, the renal parenchyme becomes thinner and suitable for transillumination. After anesthesia, the hydronephrotic kidney was split at the greater curvature with a thermal cautery and then fixed in a water chamber containing Kreb's solution. The renal tissue was transilluminated and microscopically visualized using water immersion objectives. Renal microvessels including arcuate and interlobular arteries, afferent and efferent arterioles and glomerular capillaries could be easily observed on a display monitor at a final magnification of 2, 700 times. Topical application of angiotensin II elicited constriction of the interlobular artery and afferent and efferent arterioles dose-dependently. Thus, this preparation is a unique model allowing visualization of the whole renal vascular tree in vivo.View full abstractDownload PDF (7897K) -
Naoyuki HIRONAKA, Yasuko KOHNO, Tomoji YANAGITA1998 Volume 112 Issue 4 Pages 257-266
Published: 1998
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSThe stimulating effect of antiparkinsonian drugs, talipexole and bromocriptine, on the striatal postsynaptic dopamine receptors were studied by measuring contralateral rotational behavior in rats. The nigro-striatal dopamine system of rats was degenerated by unilateral injection of 6-hydroxydopamine (6-OHDA, 8 μg rat) into substantia nigra. By subcutaneous administration, talipexole at 0.16 mg, kg and bromocriptine at 10.24 mg/kg induced significantly increased rotational behavior to the contralateral direction to the lesioned side. The onset of the effect was 30 min for talipexole and 90 min for bromocriptine. By intragastric administration, talipexole at 0.4 mg/kg and bromocriptine at 20.48 mg/kg significantly increased the rotational behavior, and the onset of the effect was 60 min for talipexole and 180 min for bromocriptine. Rotational behavior induced by talipexole was suppressed by a D2 antagonist, sulpiride (40 mg/kg, s.c.), but not by a D1 antagonist, SCH23390 (1 mg/kg, s.c.). In contrast, rotational behavior induced by bromocriptine was suppressed by both sulpiride and SCH23390. These results indicated that when the nigrostriatal dopaminergic functions are disrupted, talipexole stimulates the striatal postsynaptic dopamine receptors at much lower doses than bromocriptine. Also it was indicated that the stimulating effect of talipexole is solely mediated by dopamine D2 receptors, whereas the effect of bromocriptine is mediated by both D1 and D2 receptors.View full abstractDownload PDF (2002K) -
Mitsugu HACHISU, Misako NOMURA, Kazuyuki FUJISHIMA1998 Volume 112 Issue 4 Pages 267-274
Published: 1998
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSAmrinone (5-amino (3, 4'-bibyridin) 6- (1H) -one), an inhibitor of c-AMP-specific phosphodiesterases, has been used clinically as an inodilator. We have investigated the effect of amrinone on neointimal hyperplasia inrat carotid artery after balloon injury. When amrinone was administered subcutaneously to rats at a dose of 10 mg/kg/day for 14 days, significant reduction of neointimal thickness was noted. Four days treatment with amrinone, however, failed to reduce the intimal thickness. To investigate the mode of action to reduce intimal thickness, we tried to study the effects of amrinone on platelet aggregation and the proliferation of aortic smooth muscle cells. Amrinone produced a dose-dependent inhibition of ADP-induced rat platelet ag-gregation in vitro as well as ex vivo in rats. The proliferation of human aortic smooth muscle cells in culture stimulated with FBS or PDGF was also inhibited by amrinone. These results indicate that amrinone may have potential to prevent vascular neointimal hyperplasia in clinical balloon injury through inhibition of vascular smooth muscle cell growth and platelet aggregation.View full abstractDownload PDF (7596K) -
1998 Volume 112 Issue 4 Pages a53-a70
Published: 1998
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSDownload PDF (4562K) -
1998 Volume 112 Issue 4 Pages a71-a94
Published: 1998
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSDownload PDF (5794K)
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