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1.
Ion channels selective for chloride ions are present in all biological membranes, where they regulate the cell volume or membrane potential. Various chloride channels from mitochondrial membranes have been described in recent years. The aim of our study was to characterize the effect of stilbene derivatives on single-chloride channel activity in the inner mitochondrial membrane. The measurements were performed after the reconstitution into a planar lipid bilayer of the inner mitochondrial membranes from rat skeletal muscle (SMM), rat brain (BM) and heart (HM) mitochondria. After incorporation in a symmetric 450/450 mM KCl solution (cis/trans), the chloride channels were recorded with a mean conductance of 155 ± 5 pS (rat skeletal muscle) and 120 ± 16 pS (rat brain). The conductances of the chloride channels from the rat heart mitochondria in 250/50 mM KCl (cis/trans) gradient solutions were within the 70–130 pS range. The chloride channels were inhibited by these two stilbene derivatives: 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS) and 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid (SITS). The skeletal muscle mitochondrial chloride channel was blocked after the addition of 1 mM DIDS or SITS, whereas the brain mitochondrial channel was blocked by 300 μM DIDS or SITS. The chloride channel from the rat heart mitochondria was inhibited by 50–100 μM DIDS. The inhibitory effect of DIDS was irreversible. Our results confirm the presence of chloride channels sensitive to stilbene derivatives in the inner mitochondrial membrane from rat skeletal muscle, brain and heart cells.  相似文献   

2.
The objective of this study was to define the relationship between peroxyl radical-mediated cytotoxicity and lipid, protein and sulfhydryl oxidation using human erythrocytes as the target mammalian cell. We found that incubation of human erythrocytes with the peroxyl radical generator 2,2' azobis (2-amidinopropane) hydrochloride (AAPH) resulted in a time and dose-dependent increase in hemolysis such that at 50 mM AAPH maximum hemolysis was achieved at 120min. Hemolysis was inhibited by hypoxia and by the addition of certain water soluble free radical scavengers such as 5-aminosalicylic acid (5-ASA), 4-ASA, N-acetyl-5-ASA and dimethyl thiourea. Peroxyl radical-mediated hemolysis did not appear to involve significant peroxidation of erythrocyte lipids nor did they enhance protein oxidation at times preceding hemolysis. Peroxyl radicals did however, significantly reduce by approximately 80% the intracellular levels of GSH and inhibit by approximately 90% erythrocyte Ca2+ -Mg2+ ATPase activity at times preceding the hemolytic event. Our data as well as others suggest that extracellular oxidants promote the oxidation of intracellular compounds by interacting with certain redox active membrane components. Depletion of intracellular GSH stores using diamide did not result in hemolysis suggesting that oxidation of GSH alone does not promote hemolysis. Taken together, our data suggest that neither GSH oxidation, lipid peroxidation nor protein oxidation alone can account for peroxyl radical-mediated hemolysis. It remains to be determined whether free radical-mediated inactivation of Ca2+-Mg2+ ATPase is an important mechanism in this process.  相似文献   

3.
Fumonisin B1 (FB1) causes equine leukoencephalomalacia, porcine pulmonary edema, and liver tumors and chronic nephritis in rats. To investigate mechanisms by which FB1 induces toxicity, effects of FB1 on cellular glutathione (GSH) redox status and GSH depletion on FB1 toxicity in pig kidney (LLC-PK1) cells were studied. Treatment of LLC-PK1 cells with 50 μM FB1 for 24 hours significantly decreased cellular GSH contents from 56 ± 3.2 to 42.7 ± 4.4 nmol/mg protein (p < 0.05) and increased the activities of glutathione reductase (GR) from 25.7 ± 2.4 to 35.7 ± 5.0 μmol NADPH/mg protein (p < 0.05). The activities of glutathione peroxidase (GSHpx), catalase, and Cu,Zn-superoxide dismutase (SOD) were not changed by this treatment. Treatment of LLC-PK1 cells for 12 hours with 0.1. mM buthionine sulfoximine (BSO), a selective inhibitor of the enzyme γ-glutamylcysteine synthetase that catalyzes the rate-limiting reaction in de novo GSH synthesis, decreased cellular GSH levels to about 20% of that found in the control cells. The cells pretreated with 0.1 mM BSO for 12 hours were significantly sensitized to the FB1 cytotoxicity as determined by a long-term survival assay (p < 0.05). The results demonstrate that FB1 changes GSH redox cycle status in LLC-PK1 cells, and GSH may play a role in cytoprotection against FB1 toxicity. © 1997 John Wiley & Sons, Inc.  相似文献   

4.
通过对低渗溶血过程、荧光淬灭效应及阴离子跨膜通透性的研究,探讨了苯肼对红细胞膜结构和功能的影响。苯肼浓度0.01mM时,低渗溶血的K_1快过程开始变慢,表明膜脂质流动性的降低。苯肼浓度增至0.1mM后,膜和变性血红蛋白的结合大为增强,这种膜结构的变化提高了阴离子的跨膜通透性。  相似文献   

5.
Summary. Glutathione (reduced form GSH and oxidized form GSSG) constitutes an important defense against oxidative stress in the brain, and taurine is an inhibitory neuromodulator particularly in the developing brain. The effects of GSH and GSSG and glycylglycine, γ-glutamylcysteine, cysteinylglycine, glycine and cysteine on the release of [3H]taurine evoked by K+-depolarization or the ionotropic glutamate receptor agonists glutamate, kainate, 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and N-methyl-D-aspartate (NMDA) were now studied in slices from the hippocampi from 7-day-old mouse pups in a perfusion system. All stimulatory agents (50 mM K+, 1 mM glutamate, 0.1 mM kainate, 0.1 mM AMPA and 0.1 mM NMDA) evoked taurine release in a receptor-mediated manner. Both GSH and GSSG significantly inhibited the release evoked by 50 mM K+. The release induced by AMPA and glutamate was also inhibited, while the kainate-evoked release was significantly activated by both GSH and GSSG. The NMDA-evoked release proved the most sensitive to modulation: L-Cysteine and glycine enhanced the release in a concentration-dependent manner, whereas GSH and GSSG were inhibitory at low (0.1 mM) but not at higher (1 or 10 mM) concentrations. The release evoked by 0.1 mM AMPA was inhibited by γ-glutamylcysteine and cysteinylglycine, whereas glycylglycine had no effect. The 0.1 mM NMDA-evoked release was inhibited by glycylglycine and γ-glutamylcysteine. In turn, cysteinylglycine inhibited the NMDA-evoked release at 0.1 mM, but was inactive at 1 mM. Glutathione exhibited both enhancing and attenuating effects on taurine release, depending on the glutathione concentration and on the agonist used. Both glutathione and taurine act as endogenous neuroprotective effectors during early postnatal life. Authors’ address: Prof. Simo S. Oja, Brain Research Center, Medical School, FI-33014 University of Tampere, Finland  相似文献   

6.
7.
The hemolytic activity of the cell-free culture supernatant of Anabaena variabilis OL S1 was investigated using the hemolysis of rabbit erythrocytes as an assay. The culture medium of A. variabilis started to exhibit hemolytic activity at the late exponential growth phase, and maximized at the stationary phase. The hemolytic toxin is heat-stable and can be extracted in dichloromethane. The hemolytic activities under different temperature, light intensity and pH showed a high correlation with the cell densities (r=0.965, 0.951, 0.865, respectively), and the optimum condition is 28~30°C, pH 7.5~8.0, light intensity 120 μmol photons m−2s−1. The addition of 10~20 μg mL−1 chloramphenicol, an inhibitor of protein synthesis, exhibited no marked suppression on the hemolytic activity. The supplement of 1~20 μg mL−1 glycerol increased the hemolytic activity significantly, suggesting that synthesis of hemolysin was dependent on carbohydrate and lipid metabolism. The spectrum of erythrocyte sensitivity to the hemolysin indicated that rabbit erythrocytes were more sensitive to the hemolysin than were rat and human erythrocytes. Goldfish and cat erythrocytes were, however, insensitive to the hemolytic toxin of A. variabilis.  相似文献   

8.
In the present study we investigate the biochemical properties of the members of NPP family in synaptosomes prepared from rat heart left ventricles. Using p-nitrophenyl-5′-thymidine monophosphate (p-Nph-5′-TMP) as substrate for E-NPPs in rat cardiac synaptosomes, we observed an alkaline pH dependence, divalent cation dependence and the K M value corresponded to 91.42 ± 13.97 μM and the maximal velocity (V max ) value calculated was 63.79 ± 3.59 nmol p-nitrophenol released/min/mg of protein (mean ± SD, n = 4). Levamisole (1 mM), was ineffective as inhibitor of p-Nph-5′-TMP hydrolysis in pH 8.9 (optimum pH for the enzyme characterized). Suramin (0.25 mM) strongly reduced the hydrolysis of p-Nph-5′-TMP by about 46%. Sodium azide (10 and 20 mM) and gadolinium chloride (0.3 and 0.5 mM), E-NTPases inhibitors, had no effects on p-Nph-5′-TMP hydrolysis. RT-PCR analysis of left ventricle demonstrated the expression of NPP2 and NPP3 enzymes, but excluded the presence of NPP1 member. By quantitative real-time PCR we identified the NPP3 as the enzyme with the highest expression in rat left ventricle. The demonstration of the presence of the E-NPP family in cardiac system, suggest that these enzymes could contribute with the fine-tuning control of the nucleotide levels at the nerve terminal endings of left ventricles that are involved in several cardiac pathologies.  相似文献   

9.
The in vitro hemolytic activity of 4 isolates ofTrichomonas vaginalis was investigated. Repetitive hemolysis assays of any one isolate showed cyclical fluctuations in hemolytic activity, varying over 24 hr of continuous culture. Maximal hemolytic activity was detected using trichomonads in the lag phase of the growth cycle. Investigations showed that hemolysis was a contact-dependent phenomenon and microscopic investigation of samples showed a significant correlation between hemolysis and attachment of erythrocytes to the trichomonad surface. Quantitative data from cytoadherence assays using [51Cr]-labeled erythrocytes were consistent with these observations. It is suggested that hemolytic activity is dependent upon adherence of red blood cells to the surface ofT. vaginalis.  相似文献   

10.
Cerebroside sulfate (CGS) was found to be capable of inhibiting complement-dependent hemolysis. The activity dependence of CGS-containing liposomes on their composition was studied. Mixtures of CGS with phosphatidylethanolamine, phosphatidylserine, sphingomyelin from cattle brain, cerebroside from cattle spinal cord (CG), and egg yolk phosphatidylcholine (ePC) were investigated. In the case of binary CGS/ePC mixtures, the antihemolytic activity varied nonlinearly with an increase in the mass part of CGS: it sharply increased with an increase in the CGS part from 0.3 to 0.5 and decreased by 20–30% of the maximum value with an increase in the CGS part from 0.9 to 1. On the basis of these experiments, the optimum distance between the charged groups of CGS was estimated to be 0.92–1.6 nm. In the ternary compositions of 4:3:3 CGS/ePC/polar lipid, only CG increased the activity of liposomes as compared to that of liposomes from the 4:6 CGS/ePC. The preliminary incubation of CGS-containing liposomes with complement decreased hemolysis more effectively than incubation with other components of the hemolytic system. This suggests that the interaction of CGS-containing liposomes with the complement proteins is responsible for their antihemolytic activity.  相似文献   

11.
1. The rate of red blood cell lysis by the hemolytic agent in adult worm homogenates of Schistosoma mansoni is slowed in the presence of added sugars (50 mM). 2. Trisaccharides were the most effective in slowing and reducing lysis. Disaccharides were more effective than monosaccharides. 3. The addition of sodium, potassium or lithium chloride salts (25 mM) stimulated hemolysis by the S. mansoni agent. 4. Hemolysins with known mechanisms were tested to determine the effects of added sugars (50 mM) or salts (25 mM). 5. The S. mansoni hemolytic agent responds to the addition of sugars and salts in a manner similar to small membrane pore formers.  相似文献   

12.
Summary 4-Acetamido-4-isothiocyanostilbene-2,2-disulphonic acid (SITS), an amino-reacting probe of plasma membranes, stimulated the release of insulin from micro-dissected pancreatic islets ofob/ob-mice. This effect of SITS was inhibited by adrenaline or by calcium deficiency. SITS did not inhibit the insulin-releasing action of glucose or leucine but rather potentiated the effect of glucose. In contrast, SITS markedly depressed the insulin secretory response to chloromercuribenzene-p-sulphonic acid. It is suggested that by reacting with the plasma membranes SITS may induce secretagogic ionic fluxes in the -cells. In addition, SITS apparently inhibits the secretagogic recognition of chloromercuribenzene-p-sulphonic acid, presumably by preventing the organic mercurial from reacting with certain membrane thiol groups.  相似文献   

13.
目的:研究还原型谷胱甘肽治疗儿童葡萄糖-6-磷酸脱氢酶(G-6-P-D)缺乏症并发急性溶血的临床疗效,为临床治疗提供参考。方法:选取我院2015年6月-2017年6月因葡萄糖-6-磷酸脱氢酶(G-6-P-D)缺乏症并发急性溶血的患儿78例并将其随机分为两组,每组39例。对照组予以停用氧化类药物,卧床休息,水化、碱化尿液,贫血严重者输注去白红细胞治疗;观察组在对照组基础上加用还原型谷胱甘肽治疗。观察和比较两组患儿第1天、第2天、第3天小便恢复率以及平均恢复时间,血清总胆红素第3天、第5天恢复率、平均恢复时间及平均住院时间。结果:治疗后,观察组第1天、第2天、第3天小便恢复率分别为51.3%、92.3%、100%,对照组分别为25.6%、64.1%、89.7%,观察组第1天、第2天、第3天小便恢复率均显著高于对照组(P0.05);观察组及对照组小便恢复正常平均时间分别为1.8±0.7天、2.6±0.9天,观察组明显短于对照组(P0.05);观察组第3天、第5天血清总胆红素恢复率分别为71.8%、100%,对照组为46.2%、97.4%;观察组和对照组血清总胆红素恢复正常平均时间分别为3.6±0.9天、4.1±1.0天;平均住院时间分别为2.3±0.6天、2.8±0.6天;观察组小便及血清总胆红素平均恢复时间(P0.05)、平均住院时间均显著短于对照组(P0.05)。结论:在儿童葡萄糖-6-磷酸脱氢酶缺乏并发急性溶血中应用还原型谷胱甘肽可增强其治疗疗效,缩短治疗疗程。  相似文献   

14.
Comparative plate counts were made of Staphylococcus aureus and Streptococcus pyogenes growing on blood agar supplemented with individual chemicals to abolish the swarming of Proteus. B-phenylethanol, sodium azide, and p-nitrophenyl glycerin (PNPG) were used as anti-swarm agents. Each anti-swarm agent effectively abolished swarming for 24 h, but azide failed to control swarming for longer periods of incubation. In addition, azide displayed growth inhibition towards the staphylococci and streptococci resulting in no hemolysis and reduced viable cell numbers with the streptococci. Phenylethanol showed reduced viable cell numbers with the streptococci and unreliable hemolytic reactions. At 0.1 to 0.3 mM, PNPG proved to be a superior anti-swarm agent in that it showed no growth inhibition and allowed normal hemolysis, but abolished swarming for extended periods of time. When laboratory strains of Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa. Listeria monocytogenes, and Vibrio cholerae were screened on a blood agar medium containing 0.1 mm PNPG, they displayed similar growth and hemolytic characteristics to the identical medium without PNPG.  相似文献   

15.
Glutathione (γ-glutamylcysteinylglycine, GSH and oxidized glutathione, GSSG), may function as a neuromodulator at the glutamate receptors and as a neurotransmitter at its own receptors. We studied now the effects of GSH, GSSG, glutathione derivatives and thiol redox agents on the spontaneous, K+- and glutamate-agonist-evoked releases of [3H]dopamine from mouse striatal slices. The release evoked by 25 mM K+ was inhibited by GSH, S-ethyl-, -propyl-, -butyl- and pentylglutathione and glutathione sulfonate. 5,5′-Dithio-bis-2-nitrobenzoate (DTNB) and l-cystine were also inhibitory, while dithiothreitol (DTT) and l-cysteine enhanced the K+-evoked release. Ten min preperfusion with 50 μM ZnCl2 enhanced the basal unstimulated release but prevented the activation of K+-evoked release by DTT. Kainate and 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) evoked dopamine release but the other glutamate receptor agonists N-methyl-d-aspartate (NMDA), glycine (1 mM) and trans-1-aminocyclopentane-1,3-dicarboxylate (t-ACPD, 0.5 mM), and the modulators GSH, GSSG, glutathione sulfonate, S-alkyl-derivatives of glutathione, DTNB, cystine, cysteine and DTT (all 1 mM) were without effect. The release evoked by 1 mM glutamate was enhanced by 1 mM GSH, while GSSG, glutathionesulfonate and S-alkyl derivatives of glutathione were generally without effect or inhibitory. NMDA (1 mM) evoked release only in the presence of 1 mM GSH but not with GSSG, other peptides or thiol modulators. l-Cysteine (1 mM) enhanced the glutamate-evoked release similarly to GSH. The activation by 1 mM kainate was inhibited by S-ethyl-, -propyl-, and -butylglutathione and the activation by 0.5 mM AMPA was inhibited by S-ethylglutathione but enhanced by GSSG. Glutathione alone does not directly evoke dopamine release but may inhibit the depolarization-evoked release by preventing the toxic effects of high glutamate, and by modulating the cysteine–cystine redox state in Ca2+ channels. GSH also seems to enhance the glutamate-agonist-evoked release via both non-NMDA and NMDA receptors. In this action, the γ-glutamyl and cysteinyl moieties of glutathione are involved.  相似文献   

16.
Glutathione transferase reaches 0.5–0.8 mM concentration in the cell so it works in vivo under the unusual conditions of, [S] ? [E]. As glutathione transferase lowers the pKa of glutathione (GSH) bound to the active site, it increases the cytosolic concentration of deprotonated GSH about five times and speeds its conjugation with toxic compounds that are non-typical substrates of this enzyme. This acceleration becomes more efficient in case of GSH depletion and/or cell acidification. Interestingly, the enzymatic conjugation of GSH to these toxic compounds does not require the assumption of a substrate–enzyme complex; it can be explained by a simple bimolecular collision between enzyme and substrate. Even with typical substrates, the astonishing concentration of glutathione transferase present in hepatocytes, causes an unusual “inverted” kinetics whereby the classical trends of v versus E and v versus S are reversed.  相似文献   

17.
4′-Fluoro-2′,3′-O-isopropylidenecytidine was synthesized by the treatment of 5′-O-acetyl-4′-fluoro-2′,3′-O-isopropylideneuridine with triazole and 4-chlorophenyl dichlorophosphate followed by ammonolysis. The interaction of 4′-fluoro-2′,3′-O-isopropylidenecytidine with hydroxylamine resulted in 4′-fluoro-2′,3′-O-isopropylidene-5′-O-acetyl-N 4-hydroxycytidine. The removal of the 2′,3′-O-isopropylidene groups led to acetyl derivatives of 4′-fluorouridine, 4′-fluorocytidine, and 4′-fluoro-N 4-hydroxycytidine. 4′-Fluorouridine 5′-O-triphosphate was obtained in three steps starting from 4′-fluoro-2′,3′-O-isopropylideneuridine. 4′-Fluorouridine 5′-O-triphosphate was shown to be an effective inhibitor of HCV RNA-dependent RNA polymerase and a substrate for the NTPase reaction catalyzed by the HCV NS3 protein, the hydrolysis rate being similar to that of ATP. It could also activate a helicase reaction with an efficacy of only threefold lower than that for ATP.  相似文献   

18.
The equilibrium between antioxidant function and oxidative stress is implicated in brain pathology. However, human studies on oxidant and antioxidant markers rely on postmortem tissue that might be affected by pre and postmortem factors. To evaluate the effect of these variables, we tested whether antioxidant enzymes [superoxide dismutase (SOD), catalase] glutathione (GSH) and related enzymes [gamma glutamylcysteine ligase (GCL), GSH peroxidase (GPx), GSH reductase (GR), GSH-S-transferase (GST)] and malondialdehyde (MDA, marker of lipid peroxidation) are affected in postmortem human brains (n = 50) by increase in postmortem interval (2.5–26 h), gender difference and agonal state [based on Glasgow coma scale (GCS): range: 3–15] in different anatomical regions-frontal cortex (FC), cerebellum (CB) medulla oblongata (MO), substantia nigra (SN) and hippocampus (HC). While SOD and catalase activities were relatively unaltered, GR and GPx activities were affected by agonal state (GR in CB, p < 0.05; GPx in MO, p < 0.05) indicating altered GSH dynamics during the secondary events following neuronal injury. MO, SN and HC displayed low GSH compared to FC and CB. Total GSH level was decreased with PMI (MO, p = 0.02) which could be partly attributed to increase in MDA levels with increasing PMI in MO (p < 0.05). Total GSH level was higher in CB (p < 0.017) and MO (p < 0.04) in female brains compared to males. Interestingly, HC and SN regions showed significant stability in most of the markers tested. We suggest that while SOD and catalase were relatively unaffected by the pre and postmortem factors, GSH and its metabolic enzymes were significantly altered and this was more pronounced in MO of postmortem human brains. These data highlight the influence of pre and postmortem factors on GSH dynamics and the inherent differences in brain regions, with implications for studies on brain pathophysiology employing human samples.  相似文献   

19.
Blood was obtained from 564 11-yr-old children who had participated since birth in a multidisciplinary health and development study. Serum zinc concentration did not differ between the boys and the girls (mean±SD: 91=17 μg/100 mL,n=453). Five-6% of serum zinc values were low; although there was a weak correlation with height, none of the boys with low values were below the 10th percentile for height for this group. Serum copper concentration (112±24 μg/100 mL,n=454) was unrelated to sex, height, weight, body mass index, socioeconomic status (SES), or iron status. Blood selenium concentration (49±10 ng/mL,n=564) was lower than previously reported for Dunedin children; it was higher in children in the lower SES categories. The data represent normal values for healthy, 11-yr-old NZ children.  相似文献   

20.
Background: The analgesic acetaminophen (AAP) causes a potentially fatal, hepatic centrilobular necrosis when taken in overdose. It was reported that these toxic effects of AAP are due to oxidative reactions that take place during its metabolism. Objective: In this study, we aimed to investigate the possible beneficial effect of Ginkgo biloba (EGb), an antioxidant agent, against AAP toxicity in mice. Methods: Balb/c mice were injected i.p. with: (1) vehicle, control (C) group; (2) a single dose of 50 mg/kg Ginkgo biloba extract, EGb group; (3) a single dose of 900 mg/kg i.p. acetaminophen, AAP group, and (4) EGb, in a dose of 50 mg/kg after AAP injection, AAP + EGb group. Serum ALT, AST, and tumor necrosis factor-alpha (TNF-α) levels in blood and glutathione (GSH), malondialdehyde (MDA) levels, myeloperoxidase (MPO) activity, and collagen contents in liver tissues were measured. Formation of reactive oxygen species in hepatic tissue samples was monitored by using chemiluminescence (CL) technique with luminol and lusigenin probe. Tissues were also examined microscopically. Results: ALT, AST levels, and TNF-α were increased significantly (p < 0.001) after AAP treatment, and reduced with EGb. Acetaminophen caused a significant (p < 0.05–0.001) decrease in GSH levels while MDA levels and MPO activity were increased (p < 0.001) in liver tissues. These changes were reversed by EGb treatment. Furthermore, luminol and lusigenin CL levels in the AAP group increased dramatically compared to control and reduced by EGb treatment (p < 0.01). Conclusion: Our results implicate that AAP causes oxidative damage in hepatic tissues and Ginkgo biloba extract, by its antioxidant effects protects the tissues. Therefore, its therapeutic role as a “tissue injury-limiting agent” must be further elucidated in drug-induced oxidative damage.  相似文献   

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