The Journal of Toxicological Sciences
Online ISSN : 1880-3989
Print ISSN : 0388-1350
ISSN-L : 0388-1350
Volume 12 , Issue 3
Showing 1-5 articles out of 5 articles from the selected issue
  • Masakazu NISHIMURA, Nobuaki FUJISE, Hiroya OHTANI, Osamu YAGASAKI
    1987 Volume 12 Issue 3 Pages 291-300
    Published: August 25, 1987
    Released: February 21, 2008
    JOURNALS FREE ACCESS
    Hypoxia is suggested to increase intracellular Ca&lt2+&gt, there-by affecting cellular functions. If this is the case, the effect would be modified by other treatments which also elevate intracellular levels of Ca&lt2+&gt. To test this possibility, in mouse diaphragm preparations, the effects of hypoxia were examined on twitch potentiations after application of neural conditioning pulses which are considered to elevate intracellular Ca&lt2+&gt. The effects were compared with those of 2, 4-dinitrophenol (DNP) and ouabain. Hypoxia increased the tension of twitches elicited directly or neurally with 0.1 or 0.5 Hz pulses at 36°C but not at 24°C. Paired pulses to the nerve induced a complex response profile in which the amplitude of the second twitch was enhanced (twitch facilitation). Tetanic pulses (50 Hz) to the nerve were followed by post-tetanic twitches of increased amplitude (post-tetanic twitch potentiation, PTP). Hypoxia little affected the twitch facilitation but abolished PTP at both temperatures. These effects differed from those of DNP and ouabain in some ways. Thus, present experiments indicate that hypoxia selectively influences the process which is responsible for the PTP phenomenon rather than for the twitch facilitation. It is possible that the mechanism by which hypoxia would accumulate intracellular Ca&lt2+&gt may be included in the process through which PTP occurs.
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  • Masao KIGUCHI, Jun-ichi SUDO
    1987 Volume 12 Issue 3 Pages 301-307
    Published: August 25, 1987
    Released: February 21, 2008
    JOURNALS FREE ACCESS
    In this study, colorimetric method and high-performance liquid chromatographic (HPLC) method were improved and established, respectively, in order to minimize analytical errors in determination of para-aminohippuric acid (PAH) in rat urine and plasma. In terms of the colorimetric method, an operative step following addition of Tsuda reagent was modified as follows: after the addition of Tsuda reagent, reaction mixture was kept at 40°C for 70 min before spectrophotometry. Linearities were observed both in the higher range of 0 and 2.5 to 12.5 μg and in the lower range of 0 and 100 to 1, 000 ng per test tube, and its practical detection limit was 100 ng per test tube. In terms of HPLC method, using a reversed-phase column (Nucleosil 5 C&lt18&gt), PAH was separated by a mobile phase of acetonitrile/50 mM KH2PO4 (pH 2.8)=9/95. Linearities were observed in the higher range of 0 and 10 ng to 2 μg and in the lower range of 0 and 1 to 10 ng per injection, and its practical detection limit was 1 ng per injection. These results denote that the above two methods are applicable to routine PAH determination. In addition, our HPLC method is considered to be applicable to microassay of PAH, because its sensitivity is more sensitive and minimization of volume system is more easily achieved as compared with the colorimetric method.
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  • Sumio SHIMA, Naoko OKEYAMA, Shigeo OIKAWA, Nobu AKAMATSU
    1987 Volume 12 Issue 3 Pages 309-319
    Published: August 25, 1987
    Released: February 21, 2008
    JOURNALS FREE ACCESS
    The biochemical aspects of hepatic β-adrenergic receptors and adenylate cyclase activity in male adult rats were examined during chronic treatment of a β-adrenergic antagonist, propranolol. The blockade of β-adrenergic nervous systems for 7 to 10 days produced a considerable elevation of basal, glucagon, sodium fluoride, and 5′-guanylylimidodiphosphate, Gpp (NH)p-stimulated enzyme activity with a negligible response to a β-adrenergic agonist, isoproterenol. There was no alteration in the density or the affinity of β-adrenergic receptors for the agonist during the treatment. Guanine nucleotides have failed to induce a transformation of the higer affinity to the lower affinity state of β-adrenergic receptors of the hepatic membrane derived either from control or the propranolol-treated animals. The activity of stimulatory guanine nucleotide regulatory proteins (Ns)in the enzyme, assessed by ADP-ribosylation was also not altered by the antagonist. These results suggest that the mechanism of the observed sensitization of adenylate cyclase induced by chronic β-adrenergic blockade involves facilitation of Ns interaction with the catalytic subunit of the enzyme with no change in the β-adrenergic receptor functions.
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  • Dongsik BANG, Takayoshi HONMA, Taiich SAITO, Shojiro NAKAGAWA, Hiroaki ...
    1987 Volume 12 Issue 3 Pages 321-328
    Published: August 25, 1987
    Released: February 21, 2008
    JOURNALS FREE ACCESS
    We used electron microscopy and electron microscopic X-ray spectroanalysis to examine the biopsies taken from erythema nodosum-like lesions of 20 patients with Behcet's disease. Electron-dense degenerated endothelial cells were found in the microcirculatory beds of the dermis and subcutaneous fat. However, electron microscopic X-ray spectroanalysis failed to demonstrate the localization of either chlorine or base metals in those degenerated endothelial cells. Moreover, neither in ultra-structurally normal endothelial cells, nor in infiltrating macrophages of erythema nodosum-like lesions the positive deposit of chlorine or base metals could not be detected. The results of this analysis suggest that environmental factors do not play an etiologic role in this disease. Significance of the degeneration of endothelial cells is not clear present.
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  • Toshio MASAOKA, Fumiaki AKAHORI, Shigeyuki ARAI, Kazuko SAKAGUCHI
    1987 Volume 12 Issue 3 Pages 329-340
    Published: August 25, 1987
    Released: February 21, 2008
    JOURNALS FREE ACCESS
    The purpose of this study was to characterize paraquat toxicity in monkeys and to determine the feasibility of using the monkey as an animal model for the study of paraquat-induced pulmonary fibrosis in humans. Sixteen Japanese monkeys (Macaca fuscata), more than 3.5 years of age, with bodyweight ranging from 3.2 kg to 10.2kg, were randomly divided into two groups. They were administered paraquat dichloride (PQ) by injection (s.c.) at a dose of 2.0 mg/kg bodyweight (12 monkeys) or s.c. saline, at a dose of 0.2 ml/kg bodyweight (control group, 4 monkeys), every two days for a period of four to five times. Eight monkeys (66.7%) from the PQ treatment groups expired due to subchronic PQ toxicity from days 11 to 35. Four monkeys (33.3%) from the PQ treatment group and all four monkeys from the control group survived the observation period of 66 days. On day 66, all of the surviving monkeys were sacrificed and examined for possible histopathological changes and the lung hydroxyproline content was determined. Our results indicate that the concentration of free hydroxyproline and plasma fibronectin did not vary significantly. The serum ceruloplasmin for the monkeys of the PQ treatment groups was significantly increased from day 14 to 21, compared to the control group. Also the total lung collagen of both the expired and surviving monkeys in the PQ treatment groups was elevated significantly, compared to the control group. The monkeys can provide extensive opportunities for research on the mechanism and the treatment of PQ poisoning in man.
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