Free radical research communications最新文献_第8页

Direct evidence for nitric oxide stimulation of electrolyte secretion in the rat colon. 一氧化氮刺激大鼠结肠电解质分泌的直接证据。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309056511

H Tamai, T S Gaginella

{"title":"Direct evidence for nitric oxide stimulation of electrolyte secretion in the rat colon.","authors":"H Tamai, T S Gaginella","doi":"10.3109/10715769309056511","DOIUrl":"https://doi.org/10.3109/10715769309056511","url":null,"abstract":"Nitric Oxide (NO) is synthesized in the intestinal tract and may serve as a physiological regulator of intestinal ion transport and/or a pathophysiologic mediator of secretory diarrhea associated with inflammatory mucosal diseases. Indirect approaches, employing inhibitors of nitric oxide synthase or compounds capable of donating NO in solution, have been used to demonstrate the effects on gastrointestinal muscle and the mucosa. To determine directly whether nitric oxide itself is capable of stimulating electrolyte secretion we mounted muscle-stripped rat distal colon in Ussing chambers and monitored short-circuit current (Isc), as an indicator of effects on mucosal ion transport. Comparisons were made to sodium nitroprusside (SNP). NO and SNP stimulated concentration-dependent (0.1 microM to 100 microM) increases in Isc, with NO being more potent than SNP. The EC50 for NO was approximately 8 microM compared to a value < 20 microM for SNP. The response to NO was immediate. In contrast, SNP required a mean lag-time of 41 +/- 4 seconds, and a significantly longer time was required for SNP to reach its maximum effect. The response to both of these agonists was blocked by bumetanide, indicating that they were stimulating a chloride ion secretory response. The cyclooxygenase inhibitor piroxicam, the neurotoxin tetrodotoxin and the inhibitor of guanylate cyclase, methylene blue, all inhibited the response to both agonists. These studies demonstrate that NO itself can stimulate chloride secretion by the rat colonic mucosa through a prostaglandin-dependent, and partially neural mechanism that may involve guanylate cyclase.","PeriodicalId":12438,"journal":{"name":"Free radical research communications","volume":"19 4","pages":"229-39"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/10715769309056511","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19282287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 80

A free radical ubiquitously associated with senescence in plants: evidence for a quinone. 一种与植物衰老普遍相关的自由基:醌的证据。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309056518

N M Atherton, G A Hendry, K Möbius, M Rohrer, J T Törring

引用次数: 32

Oxygen radicals, a failure or a success of evolution? 氧自由基，是进化的失败还是成功?

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309147343

G Barja

引用次数: 52

Antioxidant action of benzylisoquinoline alkaloids. 苯基异喹啉生物碱的抗氧化作用。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309147490

A Ubeda, C Montesinos, M Payá, C Terencio, M J Alcaraz

{"title":"Antioxidant action of benzylisoquinoline alkaloids.","authors":"A Ubeda, C Montesinos, M Payá, C Terencio, M J Alcaraz","doi":"10.3109/10715769309147490","DOIUrl":"https://doi.org/10.3109/10715769309147490","url":null,"abstract":"The antioxidant action of a series of benzylisoquinoline alkaloids has been investigated. Laudanosoline, protopapaverine, anonaine, apomorphine, glaucine, boldine, bulbocapnine, tetrahydroberberine and stepholidine produced a dose-dependent inhibition of microsomal lipid peroxidation induced by Fe2+/ascorbate, CCl4/NADPH or by Fe3+ ADP/NADPH. Apomorphine exerted the highest inhibitory effects in the three systems of induction used, with a potency higher than propyl gallate. Laudanosoline was particularly effective in the first system, while bulbocapnine and anonaine were more potent when CCl4/NADPH or Fe3(+)-ADP/NADPH were used as inducers. Laudanosoline, protopapaverine, apomorphine, tetrahydroberberine and stepholidine were also potent inhibitors of nitroblue tetrazolium (NBT) reduction. The presence of a free hydroxyl group or preferably of a catechol group is a feature relevant for inhibition of lipid peroxidation and NBT reduction, nevertheless the antioxidant activity of benzylisoquinoline alkaloids cannot be only ascribed to the formation of phenoxy radicals and other free radical species may be formed during aporphine and tetrahydroprotoberberine oxidation. The influence of this series of compounds on the time course of lipid peroxidation suggests that some of them, like apomorphine and boldine act as chain-breaking antioxidants.","PeriodicalId":12438,"journal":{"name":"Free radical research communications","volume":"18 3","pages":"167-75"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/10715769309147490","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19306047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 28

Trevor F. Slater. 特雷弗·f·斯莱特。

Free radical research communications Pub Date : 1993-01-01

M u Dianzani

引用次数: 0

Reduction of a tetrazolium salt and superoxide generation in human tumor cells (HeLa). 减少四氮唑盐和人肿瘤细胞(HeLa)中超氧化物的产生。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309147503

R H Burdon, V Gill, C Rice-Evans

{"title":"Reduction of a tetrazolium salt and superoxide generation in human tumor cells (HeLa).","authors":"R H Burdon, V Gill, C Rice-Evans","doi":"10.3109/10715769309147503","DOIUrl":"https://doi.org/10.3109/10715769309147503","url":null,"abstract":"Experiments have been carried out to explore the use of a tetrazolium salt, MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide in the detection of intracellularly generated superoxide in HeLa cells. From the use of a low molecular weight lipophilic mimic of superoxide dismutase, as well as superoxide dismutase, and inhibitors of superoxide dismutase, it is suggested that at least 20-30% of the intracellular reduction of MTT is due to superoxide. Whilst this may arise from mitochondria another possible intracellular source in HeLa cells may be xanthine oxidase. The overall rate of intracellular MTT reduction in HeLa cells is inversely dependent on levels of serum in the culture medium. Serum components with a modulatory role in this context are those with antioxidant function. Reduced MTT is also detectable extracellularly in cultures of HeLa cells and at least 80% of this is due to superoxide. Use of inhibitors suggest that whilst a small proportion (30%) may arise through an NADPH-oxidase type enzyme, other sources of extracellular superoxide in HeLa cells remain a possibility.","PeriodicalId":12438,"journal":{"name":"Free radical research communications","volume":"18 6","pages":"369-80"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/10715769309147503","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19382631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 75

The effect of oxygen at physiological levels on the detection of free radical intermediates by electron paramagnetic resonance. 生理水平的氧对电子顺磁共振检测自由基中间体的影响。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309145873

M C Krishna, A Samuni

{"title":"The effect of oxygen at physiological levels on the detection of free radical intermediates by electron paramagnetic resonance.","authors":"M C Krishna, A Samuni","doi":"10.3109/10715769309145873","DOIUrl":"https://doi.org/10.3109/10715769309145873","url":null,"abstract":"It is well known that oxygen enhances the relaxation of free radical EPR probes through spin lattice and Heisenberg spin-spin interactions with consequent effect on the line height and width. The two relaxation processes have opposing effects on the signal heights and depend on the concentration of oxygen, the incident microwave power, and the presence of other paramagnetic species. During EPR studies of chemical, biochemical, and cellular processes involving free radicals, molecular oxygen has significant magnetic influence on the EPR signal intensity of the free radical species under investigation in addition to affecting the rates of production of the primary species and the stability of the spin adduct nitroxides. These effects are often overlooked and can cause artifacts and lead to erroneous interpretation. In the present study, the effects of oxygen and ferricyanide on the EPR signal height of stable and persistent spin adduct nitroxides at commonly employed microwave powers were examined. The results show that under commonly adopted EPR spectrometer instrumental conditions, artifactual changes in the EPR signal of spin adducts occur and the best way to avoid them is by keeping the oxygen level constant using a gas-permeable cell.","PeriodicalId":12438,"journal":{"name":"Free radical research communications","volume":"18 4","pages":"239-47"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/10715769309145873","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19382048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Spin-trapping and chemiluminescence studies of neutrophils from a Holstein-Friesian calf with bovine leukocyte adhesion deficiency. 牛白细胞粘附缺陷的荷斯坦-弗里希犊牛中性粒细胞的自旋俘获和化学发光研究。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309147498

M Kuwabara, Y Nishimura, F Sato, T Takahashi, M Tajima, K Takahashi, H Nagahata

引用次数: 7

Sonochemistry of acetone and acetonitrile in aqueous solutions. A spin trapping study. 水溶液中丙酮和乙腈的声化学。一项自旋捕获研究。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.1016/0891-5849(90)90319-E

P. Riesz, T. Kondo, A. Carmichael

引用次数: 10

The superoxide scavenging activity of dihydroquinoline type derivatives (CH402 and MTDQ-DA). 二氢喹啉类衍生物(CH402和MTDQ-DA)的超氧化物清除活性。

Free radical research communications Pub Date : 1993-01-01 DOI: 10.3109/10715769309056517

L Prònai, A Blåzovics, M Horvåth, I Lång, J Fehér

引用次数: 4