• Title, Summary, Keyword: reoxygenation

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Acid Secretion and Nitric Oxide Synthase Activity in Gastric Glands Following Hypoxia/Reoxygenation and Acidosis (Hypoxia/Reoxygenation과 Acidosis가 위선세포에서 위산분비와 NO Synthase 활성에 미치는 영향)

  • Kim Hye-Young;Kim Kyung-Hwan
    • The Korean Journal of Pharmacology
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    • v.31 no.1
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    • pp.75-84
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    • 1995
  • Acid secretion and NO synthase activity were determined in isolated gastric glands following hypoxia/reoxygenation and acidosis to investigate the involvement of NO in acid secretion. Isolated gastric glands were exposed to hypoxia (30 min)/reoxygenation (1 h) and/or to acidosis (pH 6.0 and 4.0). Acid secretion was measured by the ratio of $[^{14}C]-aminopyrine$ accumulation between intra- and extraglands. NO synthase activity was determined by percent conversion to $[^{14}C]-citrulline\;from\;[^{14}C]L-arginine$, a precursor of NO. The results indicate that dibutyryl cAMP stimulated acid secretion dose-dependently but had no effect on NO synthase activity in basal gastric glands. Hypoxia/reoxygenation significantly suppressed acid secretion both in unstimulated and stimulated gastric glands, which was exaggerated by acidosis. Constitutive NO synthase, activity, not responded to dibutyryl cAMP, was also inhibited by hypoxia/reoxygenation and acidosis. In conclusion, pathologic state of gastric mucosa such as hypoxia/reoxygenation and acidosis suppresses both acid secretion and NO release but the role of NO in acid secretion stimulated by dibutyryl cAMP in basal gastric glands is not significant.

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The Effect of Vitamin C on Hypoxia/reoxygenation Induced Hepatic Injury in Isolated Perfused Rat Liver (흰쥐 관류간 모델에서 저산소 및 산소재도입시 vitamin C가 간장기능에 미치는 영향)

  • 고준일;조태순;이선미
    • Biomolecules & Therapeutics
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    • v.5 no.1
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    • pp.1-7
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    • 1997
  • This study was done to investigate the effect of vitamin C on hypoxia/reoxygenation-induced hepatic injury ul isolated perfused rat liver. Isolated livers from rats fasted 18 hours were subjected to 45 min of hypoxia followed by reoxygenation for 45 min. The perfusion medium used was Krebs-Henseleit bicarbonate buffer (pH 7.4) and 0.5 mmol/L of vitamin C was added to the perfusate. Alanine aminotransferase (ALI) and lactate dehydrogenase (LDH) levels were significantly increased by hypoxia/reoxygenation. These increases were augmented by vitamin C. Glucose output and bile flow were markedly decreased by hypoxia/reoxygenation. Vitamin C aggavated the decrease of glucose output but had little effect on bile flow. Our findings suggest that hypoxia/reoxygenation diminishes hepatic metabolic and secretory functions, and vitamin C significantly aggravates these changes.

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Changes in drug metabolism during hypoxia/reoxygenation in isolated perfused rat

  • Seo, Min-Young;Cho, Tai-Soon;Lee, Sun-Mee
    • Proceedings of the Korean Society of Applied Pharmacology
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    • pp.98-98
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    • 1997
  • This study was done to investigate the effect of vitamin E on hypoxia/reoxygenation-induced hepatic injury in isolated perfused rat liver. Rats were pretreated with vitamin E or vehicle(soybean oil). Isolated livers from fasted 18 hours were subjected to 45min of low flow hypoxia or N$_2$ hypoxia followed by reoxygenation for 30min. The perfusion medium used was KHBB(pH 7.4) and 50${\mu}$㏖/$\ell$ of ethoxycoumarin was added to the perfusate to determine the ability of hepatic drug-metabolizing systems, In low flow hypoxia model, total glutathione and oxidised glutathione levels were significantly increased by hepoxia/reoxygenation with slight increase in LDH levels. These increases were prevented by vitamin E pretreatment. In N$_2$ hypoxia model, LDH, total glutathione and oxidized glutathione levels were increased significantly by hypoxia but restored to normal level by reoxygenation. Vitamin E had little effect on this hypoxic damage. There were no significant changes in the rate of hepatic oxidation of 7-EC to 7-HC in both hepoxic models. But, the subsequent conjugation of 7-HC by sulfate or glucuronic acid were significantly decreased by hypoxia, but restored by reoxygenation in both hypoxia models. As opposed to our expectation, treatment with vitamin E aggrevated the decrease of the rate of conjugation and even inhibited the restoration by reoxygenation. Our findings suggest that hypoxia/reoxygenation diminishes phase II drug metabolizing function and this is, in part, related to decreased energy level.

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The Effects Kunnuetang and Herbs on Mouse Neuroblastoma 2a Cells Damaged by Hypoxia-reoxygenation (건뇌양(健腦揚)과 단미(單味)들이 Hypoxia-Reoxygenation에 의해 손상받은 Mouse Neuroblastoma 2a Cells에 미치는 영향(影響))

  • Yeum, Chang-Sub;Kim, Jong-Woo;Kang, Chul-Hun;Whang, Wei-Wan
    • Journal of Oriental Neuropsychiatry
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    • v.16 no.2
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    • pp.73-88
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    • 2005
  • Object : This study was designed to asses the effect of Kunnuetang and herbs on Mouse neuroblastoma 2a cells damaged by hypoxia-reoxygenation. Method : Mouse neuroblastoma 2a (N2a) cells were measured by MTT assay and LDH assay after 48h hypoxia and 6h reoxygenation. Mouse neuroblastoma 2a (N2a) cells were treated by Kunnuetang, Duchang and Daejo. Result : 1. Kunnuetang, was effective on LDH assay of hypoxia and reoxygenation. 2. Duchang and Daejo were generally effective on LDH assay of hypoxia and reoxygenation. 3. In MTT assay of hypoxia Kunnuetang was not effective. Duchung and Daejo were not generally effective on MTT assay, but in certain condition Herbs were effective. 4. In MTT assay of reoxygenation Kunnuetang and Daejo were not effective. But Duchung was effective in certain condition. Conclusion : The results suggest that Kunnuetang, Duchang and Daejo may have protective effect on vascular dementia and ad patient.

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The effects of Hwangryunhaedoktang and herbs on Mouse neuroblastoma 2a cells damaged by hypoxia-reoxygenation (황연해독탕(黃連解毒湯)이 Hypoxia-reoxygenation에 의해 손상 받은 Mouse Neuroblastoma 2a Cells에 미치는 영향(影響))

  • Ahn, Sang-Hoon;Kim, Jong-Woo;Kang, Chul-Hun;Whang, Wei-Wan
    • Journal of Oriental Neuropsychiatry
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    • v.17 no.2
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    • pp.37-59
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    • 2006
  • Objective : This study was designed to asses the effect of Hwangryunhaedoktang and herbs on Mouse neuroblastoma 2a cells damaged by hypoxia-reoxygenation. Method : Mouse neuroblastoma 2a (N2a) cells were measured by MTT assay and LDH assay after 48h hypoxia and 6h reoxygenation. Mouse neuroblastoma 2a (N2a) cells were treated by Hwangryunhaedoktang and herbs. Result : 1. Hwangryunhaedoktang was effective on LDH assay of hypoxia and reoxygenation. 2. All of herbs were generally effective on LDH assay of hypoxia and reoxygenation. In LDH assay of hypoxia, the effects of herbs depended on concentration. In MTT assay of hypoxia, Coptidis Rhizoma and Gardeniae Fructus were effective. In MTT assay of reoxygenation most of herbs were not effective. But Phellodendri Cortex was effective in high concentration. Conclusion : The results imply that Hwangryunhaedoktang and all herbs of it nay have protective effect on dementia and aging.

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Reoxygenation Stimulates EDRE(s) Release from Endothelial Cells of Rabbit Aorta

  • Suh, Suk-Hyo;Han, Jae-Jin;Park, Sung-Jin;Choi, Jai-Young;Sim, Jae-Hoon;Kim, Young-Chul;Kim, Ki-Whan
    • The Korean Journal of Physiology and Pharmacology
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    • v.3 no.4
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    • pp.393-404
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    • 1999
  • We have reported that hypoxia stimulates EDRF(s) release from endothelial cells and the release may be augmented by previous hypoxia. As a mechanism, it was hypothesized that reoxygenation can stimulate EDRF(s) release from endothelial cells and we tested the hypothesis via bioassay experiment. In the bioassay experiment, rabbit aorta with endothelium was used as EDRF donor vessel and rabbit carotid artery without endothelium as a bioassay test ring. The test ring was contracted by prostaglandin $F_{2a}\;(3{\times}10^{-6}\;M)$ which was added to the solution perfusing through the aorta. Hypoxia was evoked by switching the solution aerated with 95% $O_2/5%\;CO_2$ mixed gas to one aerated with 95% $O_2/5%\;CO_2$ mixed gas. Hypoxia/reoxygenation were interexchanged at intervals of 2 minutes (intermittent hypoxia). In some experiments, endothelial cells were exposed to 10-minute hypoxia (continuous hypoxia) and then exposed to reoxygenation and intermittent hypoxia. In other experiments, the duration of reoxygenation was extended from 2 minutes to 5 minutes. When the donor aorta was exposed to intermittent hypoxia, hypoxia stimulated EDRF(s) release from endothelial cells and the hypoxia-induced EDRF(s) release was augmented by previous hypoxia/reoxygenation. When the donor aorta was exposed to continuous hypoxia, there was no increase of hypoxia-induced EDRF(s) release during hypoxia. But, after the donor aorta was exposed to reoxygenation, hypoxia-induced EDRF(s) release was markedly increased. When the donor aorta was pretreated with nitro-L-arginine $(10^{-5}$ M for 30 minutes), the initial hypoxia-induced EDRF(s) release was almost completely abolished, but the mechanism for EDRF(s) release by the reoxygenation and subsequent hypoxia still remained to be clarified. TEA also blocked incompletely hypoxia-induced and hypoxia/reoxygenation-induced EDRF(s) release. EDRF(s) release by repetitive hypoxia and reoxygenation was completely blocked by the combined treatment with nitro-L-arginine and TEA. Cytochrome P450 blocker, SKF-525A, inhibited the EDRF(s) release reversibly and endothelin antgonists, BQ 123 and BQ 788, had no effect on the release of endothelium-derived vasoactive factors. Superoxide dismutase (SOD) and catalase inhibited the EDRF(s) release from endothelial cells. From these data, it could be concluded that reoxygenation stimulates EDRF(s) release and hypoxia/reoxygenation can release not only NO but also another EDRF from endothelial cells by the production of oxygen free radicals.

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The effects Sunghyangjungkisan-ga-pogongng and herbs on Mouse neuroblastoma 2a cells damaged by hypoxia-reoxygenation (성향정기산가보공영(星香正氣散加補公英)과 단미(單味)들이 Hypoxia-reoxygenation에 의해 손상받은 Mouse Neuroblastoma 2a Cells에 미치는 영향(影響))

  • Yoo, Jin-Suk;Kim, Jong-Woo;Kang, Chul-Hun;Whang, Wei-Wan
    • Journal of Oriental Neuropsychiatry
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    • v.16 no.1
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    • pp.19-41
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    • 2005
  • Object : This study was designed to asses the effect of Sunghyangjungkisan-ga-pogongng and herbs on Mouse neuroblastoma 2a cells damaged by hypoxia-reoxygenation. Method : Mouse neuroblastoma 2a (N2a) cells were measured by MTT assay and LDH assay after 48h hypoxia and 6h reoxygenation, Mouse neuroblastoma 2a (N2a) cells were treated by SHJG+P and herbs. Result : 1. SHJG+P was effective on LDH assay of hypoxia and reoxygenation. 2. The herbs were generally effective on LDH assay of hypoxia and reoxygenation. In MTT assay of hypoxia JP and GC were effecctive. In LDH assay of hypoxia all of herbs were effective. DMH, BC, SY, NS were more effective than other herbs. In LDH assay of reoxygenation KH, BH, BBR, DMH were especially effective. In MTT assay of reoxygenation most of herbs were not effective. But GC, SY, BH, JP were effective. Conclusion : The results imply that SHJG+P and all of berbs may have protective effect on dementia and GC, SY, BH, JP may have protective effect.

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Effect of Trolox C on Hypoxia/Reoxygenation-Induced Injury in Isolated Perfused Rat Liver

  • Lee, Sun-Mee;Cho, Tai-Soon
    • Archives of Pharmacal Research
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    • v.20 no.5
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    • pp.471-475
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    • 1997
  • Livers isolated from 18 hours fasted rats were subjected to N$_{2}$ hypoxia (for 45 min) followed by reoxygenation (for 45 min). The perfusion medium used was Krebs-Henseleit bicarbonate buffer (KHBB, pH 7.4). Lactate and alanine were added as gluconeogenic and ureagenic substrates and Trolox C was also added to perfusate. Oxygen consumption, lactate dehydrogenase (LDH), alanine transaminase (ALT), total glutathione, oxidized glutathione, bile flow, glucose and urea were measured. After hypoxia oxygen consumption significantly dropped but Trolox C had no influence on this decrease. ALT and LDH were significantly increased by hypoxia/reoxygenation. This increase was markedly attenuated in the presence of Trolox C. The total glutathione and oxidized glutathione efflux increased following hypoxia, which were prevented by the treatment of Trolox C. Bile flow rate decreased following hypoxia/reoxygenation but did not continue to decrease in the reoxygenation phase by Trolox C. Following hypoxia/reoxygenation glucose and urea releases decreased. Trolox C had no influence on inhibition of glucose and urea production. These results suggest that Trolox C protected the liver cells against hypoxia/reoxygenation injury, yielding further evidence for a causative role of oxidative stress in this model.

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The Replicon Initiation Burst Released by Reoxygenation of Hypoxic T24 Cells is Accompanied by Changes of MCM2 and Cdc7

  • Martin, Leenus
    • BMB Reports
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    • v.40 no.5
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    • pp.805-813
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    • 2007
  • Although MCM2 is obviously important for the initiation of eukaryotic DNA replication, its role in $O_2$ dependent regulation of replicon initiation is poorly understood. In this report, I analysed the changes of MCM2 during the transition from hypoxically suppressed replicon initiation to the burst of initiation triggered by reoxygenation in T24 cells. A high level of chromatin bound and nucleosolic MCM2 was found under the hypoxic replicon arrest. In contrast low cytosolic MCM2 was noticed. Recovery of $O_2$ induced phosphorylation and diminution of chromatin bound MCM2, whereas cytosolic MCM2 increased. The level of chromatin bound Cdc7 did not change significantly upon reoxygenation. However, after reoxygenation, significant phosphorylation of Cdc7 and an increase of coimmunoprecipitation with its substrate (MCM2) were observed. This provides a hint that reoxygenation may promote the kinase activity of Cdc7. These changes might be the critical factors in $O_2$ dependent regulation of replicon initiation. Moreover, phosphorylation of Cdc7 by Cdk2 can be observed in vitro, but seems to fail to regulate the level of chromatin bound Cdc7 as well as the changes of MCM2 in response to reoxygenation of hypoxically suppressed cells.

Susceptibility of Cigarette Smoke Condensate-Exposed Human Bronchial Epithelial Cells to Hypoxia-Reoxygenation (담배연기 농축액 처리에 의해 유도된 사람 기관지 상피세포주의 Hypoxia-Reoxygenation에 대한 민감성)

  • Lee, In-Ja;Choi, Eun-Mi
    • Environmental Analysis Health and Toxicology
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    • v.24 no.1
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    • pp.53-61
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    • 2009
  • 사람 기관지상피세포주인 BEAS-2B에 담배연기농축액(CSC)을 처리하여 유도된 1198 세포주는 대조군 세포주인 1799에 비해 현저하게 낮은 glutathione 농도와 낮은 glutamate-cysteine ligase(GCL), glutathione peroxidase(GPx), glucose-6-phosphate dehydrogenase(G6PD), catalase 효소활성을 보였다. 두 세포주를 포도당 존재 하에서 4시간 hypoxia 처리 후 reoxygenation 하면서 시간에 따른 세포의 항산화계 활성을 측정한 결과, 1799 세포주에서는 의미 있는 변화가 관찰되지 않은 반면, 1198 세포주에서는 hypoxia 처리에 의해 glutathione의 농도 및 GSH/GSSG 비와 G6PD 활성이 감소되었고, reoxygenation 기에는 GPx, glutathione reductase(GRd), G6PD, superoxide dismutase 활성이 감소되었다. 그러나 reoxygenation 2시간 이후에는 GRd와 G6PD 활성의 회복이 관찰되었으며, 그 결과 GSH/GSSG 비율이 회복되었다. 이 실험 결과는 CSC가 능력을 현저히 저하시킬 수 있음을 보여준다. Glutathione은 hypoxia-reoxygenation에 의한 산화적 스트레스 하에서 항산화제로서의 역할뿐 아니라, 세포 내 GSH/GSSG 비의 변화를 통해 산화적 스트레스에 대한 항산화계의 적응 반응 여부를 결정하는 중요한 인자로 작용할 것으로 보여진다.