S. Thom, V. Bhopale, D. Fisher, Y. Manevich, Paul L Huang, D. Buerk
{"title":"氧分压升高对大脑皮层一氧化氮合酶的刺激:氧化应激反应。","authors":"S. Thom, V. Bhopale, D. Fisher, Y. Manevich, Paul L Huang, D. Buerk","doi":"10.1002/NEU.10044","DOIUrl":null,"url":null,"abstract":"The purpose of this investigation was to determine the impact of elevated partial pressures of O(2) on the steady state concentration of nitric oxide ((*)NO) in the cerebral cortex. Rodents with implanted O(2)- and (*)NO-specific microelectrodes were exposed to O(2) at partial pressures from 0.2 to 2.8 atmospheres absolute (ATA) for up to 45 min. Elevations in (*)NO concentration occurred with all partial pressures above that of ambient air. In rats exposed to 2.8 ATA O(2) the increase was 692 +/- 73 nM (S.E., n = 5) over control. Changes were not associated with alterations in concentrations of nitric oxide synthase (NOS) enzymes. Based on studies with knock-out mice lacking genes for neuronal NOS (nNOS) or endothelial NOS (eNOS), nNOS activity contributed over 90% to total (*)NO elevation due to hyperoxia. Immunoprecipitation studies indicated that hyperoxia doubles the amount of nNOS associated with the molecular chaperone, heat shock protein 90 (Hsp90). Both (*)NO elevations and the association between nNOS and Hsp90 were inhibited in rats infused with superoxide dismutase. Elevations of (*)NO were also inhibited by treatment with the relatively specific nNOS inhibitor, 7 nitroindazole, by the ansamycin antibiotics herbimycin and geldanamycin, by the antioxidant N-acetylcysteine, by the calcium channel blocker nimodipine, and by the N-methyl-D-aspartate inhibitor, MK 801. Hyperoxia did not alter eNOS association with Hsp90, nor did it modify nNOS or eNOS associations with calmodulin, the magnitude of eNOS tyrosine phosphorylation, or nNOS phosphorylation via calmodulin kinase. Cerebral cortex blood flow, measured by laser Doppler flow probe, increased during hyperoxia and may be causally related to elevations of steady state (*)NO concentration. We conclude that hyperoxia causes an increase in (*)NO synthesis as part of a response to oxidative stress. Mechanisms for nNOS activation include augmentation in the association with Hsp90 and intracellular entry of calcium.","PeriodicalId":16540,"journal":{"name":"Journal of neurobiology","volume":"37 1","pages":"85-100"},"PeriodicalIF":0.0000,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"95","resultStr":"{\"title\":\"Stimulation of nitric oxide synthase in cerebral cortex due to elevated partial pressures of oxygen: an oxidative stress response.\",\"authors\":\"S. Thom, V. Bhopale, D. Fisher, Y. Manevich, Paul L Huang, D. Buerk\",\"doi\":\"10.1002/NEU.10044\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The purpose of this investigation was to determine the impact of elevated partial pressures of O(2) on the steady state concentration of nitric oxide ((*)NO) in the cerebral cortex. Rodents with implanted O(2)- and (*)NO-specific microelectrodes were exposed to O(2) at partial pressures from 0.2 to 2.8 atmospheres absolute (ATA) for up to 45 min. Elevations in (*)NO concentration occurred with all partial pressures above that of ambient air. In rats exposed to 2.8 ATA O(2) the increase was 692 +/- 73 nM (S.E., n = 5) over control. Changes were not associated with alterations in concentrations of nitric oxide synthase (NOS) enzymes. Based on studies with knock-out mice lacking genes for neuronal NOS (nNOS) or endothelial NOS (eNOS), nNOS activity contributed over 90% to total (*)NO elevation due to hyperoxia. Immunoprecipitation studies indicated that hyperoxia doubles the amount of nNOS associated with the molecular chaperone, heat shock protein 90 (Hsp90). Both (*)NO elevations and the association between nNOS and Hsp90 were inhibited in rats infused with superoxide dismutase. Elevations of (*)NO were also inhibited by treatment with the relatively specific nNOS inhibitor, 7 nitroindazole, by the ansamycin antibiotics herbimycin and geldanamycin, by the antioxidant N-acetylcysteine, by the calcium channel blocker nimodipine, and by the N-methyl-D-aspartate inhibitor, MK 801. Hyperoxia did not alter eNOS association with Hsp90, nor did it modify nNOS or eNOS associations with calmodulin, the magnitude of eNOS tyrosine phosphorylation, or nNOS phosphorylation via calmodulin kinase. Cerebral cortex blood flow, measured by laser Doppler flow probe, increased during hyperoxia and may be causally related to elevations of steady state (*)NO concentration. We conclude that hyperoxia causes an increase in (*)NO synthesis as part of a response to oxidative stress. 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引用次数: 95
摘要
本研究的目的是确定O(2)分压升高对大脑皮层一氧化氮((*)NO)稳态浓度的影响。植入O(2)-和(*)NO特异性微电极的啮齿动物在0.2至2.8大气压(ATA)的O(2)环境中暴露长达45分钟。(*)NO浓度在所有分压高于环境空气时均出现升高。在暴露于2.8 ATA O(2)的大鼠中,比对照组增加692±73 nM (s.e., n = 5)。这些变化与一氧化氮合酶(NOS)酶浓度的变化无关。根据对缺乏神经元NOS (nNOS)或内皮NOS (eNOS)基因的敲除小鼠的研究,nNOS活性对高氧引起的总NO(*)升高的贡献超过90%。免疫沉淀研究表明,高氧使与分子伴侣热休克蛋白90 (Hsp90)相关的nNOS数量增加一倍。灌注超氧化物歧化酶后,(*)NO升高及nNOS与Hsp90的相关性均被抑制。相对特异性的nNOS抑制剂7硝基吲唑、安霉素类抗生素herbimycin和格尔达霉素、抗氧化剂n -乙酰半胱氨酸、钙通道阻滞剂尼莫地平和n -甲基- d -天冬氨酸抑制剂MK 801也能抑制NO的升高。高氧没有改变eNOS与Hsp90的关联,也没有改变nNOS或eNOS与钙调蛋白的关联,也没有改变eNOS酪氨酸磷酸化的幅度,或通过钙调蛋白激酶磷酸化nNOS。激光多普勒血流探头测量的大脑皮层血流量在高氧状态下增加,可能与稳态NO浓度升高有因果关系。我们得出结论,高氧导致(*)NO合成增加,这是对氧化应激反应的一部分。nNOS激活的机制包括与Hsp90相关的增强和钙的细胞内进入。
Stimulation of nitric oxide synthase in cerebral cortex due to elevated partial pressures of oxygen: an oxidative stress response.
The purpose of this investigation was to determine the impact of elevated partial pressures of O(2) on the steady state concentration of nitric oxide ((*)NO) in the cerebral cortex. Rodents with implanted O(2)- and (*)NO-specific microelectrodes were exposed to O(2) at partial pressures from 0.2 to 2.8 atmospheres absolute (ATA) for up to 45 min. Elevations in (*)NO concentration occurred with all partial pressures above that of ambient air. In rats exposed to 2.8 ATA O(2) the increase was 692 +/- 73 nM (S.E., n = 5) over control. Changes were not associated with alterations in concentrations of nitric oxide synthase (NOS) enzymes. Based on studies with knock-out mice lacking genes for neuronal NOS (nNOS) or endothelial NOS (eNOS), nNOS activity contributed over 90% to total (*)NO elevation due to hyperoxia. Immunoprecipitation studies indicated that hyperoxia doubles the amount of nNOS associated with the molecular chaperone, heat shock protein 90 (Hsp90). Both (*)NO elevations and the association between nNOS and Hsp90 were inhibited in rats infused with superoxide dismutase. Elevations of (*)NO were also inhibited by treatment with the relatively specific nNOS inhibitor, 7 nitroindazole, by the ansamycin antibiotics herbimycin and geldanamycin, by the antioxidant N-acetylcysteine, by the calcium channel blocker nimodipine, and by the N-methyl-D-aspartate inhibitor, MK 801. Hyperoxia did not alter eNOS association with Hsp90, nor did it modify nNOS or eNOS associations with calmodulin, the magnitude of eNOS tyrosine phosphorylation, or nNOS phosphorylation via calmodulin kinase. Cerebral cortex blood flow, measured by laser Doppler flow probe, increased during hyperoxia and may be causally related to elevations of steady state (*)NO concentration. We conclude that hyperoxia causes an increase in (*)NO synthesis as part of a response to oxidative stress. Mechanisms for nNOS activation include augmentation in the association with Hsp90 and intracellular entry of calcium.