顺铂诱导胃癌SGC-7901细胞凋亡作用及其对线粒体膜电位变化的研究

目的研究线粒体膜电位在顺铂诱导胃癌细胞凋亡中的作用机制。方法采用MTT比色法测定顺铂对胃癌SGC7901细胞的生长抑制曲线;将胃癌SGC7901细胞分成对照组及10μg/ml顺铂组处理,用流式细胞仪（FCS）分别检测线粒体膜电位（Δψm）和分析细胞周期变化情况。结果顺铂可明显抑制胃癌细胞增殖。在24h后可见细胞大部分受阻于G1期,且出现了典型的凋亡峰;在10h后线粒体膜电位明显降低。结论顺铂诱导胃癌SGC-7901细胞凋亡的途径可能是通过使线粒体膜通透性的改变,膜电位的下降来而实现的。     

Mitogen-activated protein kinases (MAPKs) mediate SIN-1/glucose deprivation-induced death in rat primary astrocytes

Peroxynitrite is a potent neurotoxic molecule produced from a reaction between NO and superoxide and induces NO-mediated inflammation under neuropathological conditions. Previously, we reported that glucose deprivation induced ATP depletion and cell death in immunostimulated astrocytes, which was mainly due to peroxynitrite. In this study, the role of MAPKs (ERK1/2, p38MAPK, and JNK1SAPK) signal pathway in the SIN-1/glucose deprivation-induced death of astrocytes was examined. A combined treatment with glucose deprivation and 50 microM SIN-1, an endogenous peroxynitrite generator, rapidly and markedly increased the death in rat primary astrocytes. Also, SIN-1/glucose deprivation resulted in the activation of MAPKs, which was significantly blocked by the treatment with 20 microM MAPKs inhibitors (ERK1/2, PD98059; p38MAPK, SB203580; JNK/SAPK, SP600125). Interestingly, SIN-1/glucose deprivation caused the loss of intracellular ATP level, which was significantly reversed by MAPKs inhibitors. These results suggest that the activation of MAPKs plays an important role in SIN-1/glucose deprivation-induced cell death by regulating the intracellular ATP level.     

Decreased in vitro fertility in male rats exposed to fluoride-induced oxidative stress damage and mitochondrial transmembrane potential loss

Fluorosis, caused by drinking water contamination with inorganic fluoride, is a public health problem in many areas around the world. The aim of the study was to evaluate the effect of environmentally relevant doses of fluoride on in vitro fertilization (IVF) capacity of spermatozoa, and its relationship to spermatozoa mitochondrial transmembrane potential (DeltaPsi(m)). Male Wistar rats were administered at 5 mg fluoride/kg body mass/24 h, or deionized water orally for 8 weeks. We evaluated several spermatozoa parameters in treated and untreated rats: i) standard quality analysis, ii) superoxide dismutase (SOD) activity, iii) the generation of superoxide anion (O(2)(-)), iv) lipid peroxidation concentration, v) ultrastructural analyses of spermatozoa using transmission electron microscopy, vi) DeltaPsi(m), vii) acrosome reaction, and viii) IVF capability. Spermatozoa from fluoride-treated rats exhibited a significant decrease in SOD activity (~33%), accompanied with a significant increase in the generation of O(2)() (~40%), a significant decrease in DeltaPsi(m) (~33%), and a significant increase in lipid peroxidation concentration (~50%), relative to spermatozoa from the control group. Consistent with this finding, spermatozoa from fluoride-treated rats exhibited altered plasmatic membrane. In addition, the percentage of fluoride-treated spermatozoa capable of undergoing the acrosome reaction was decreased relative to control spermatozoa (34 vs. 55%), while the percentage fluoride-treated spermatozoa capable of oocyte fertilization was also significantly lower than the control group (13 vs. 71%). These observations suggest that subchronic exposure to fluoride causes oxidative stress damage and loss of mitochondrial transmembrane potential, resulting in reduced fertility.     

Differences between rat primary cortical neurons and astrocytes in purine release evoked by ischemic conditions

In the brain, the levels of adenosine increase up to 100-fold during cerebral ischernia; however, the roles of specific cell types, enzymatic pathways and membrane transport processes in regulating intra- and extracellular concentrations of adenosine are poorly characterized. Rat primary cortical neurons and astrocytes were incubated with [(3)H]adenine for 30 min to radiolabel intracellular ATP. Cells were then treated with buffer, glucose deprivation (GD), oxygen-glucose deprivation (OGD), 100 micro M sodium cyanide (NaCN) or 500 micro M iodoacetate (IAA) for 1 h to stimulate the metabolism of ATP and cellular release of [(3)H]purines. The nucleoside transport inhibitor dipyridamole (DPR) (10 micro M), the adenosine kinase inhibitor iodotubercidin (ITU) (1 micro M), the adenosine deaminase inhibitor EHNA (1 micro M) and the purine nucleoside phosphorylase inhibitor BCX-34 (10 micro M) were tested to investigate the contribution of specific enzymes and transporters in the metabolism and release of purines from each cell type. Our results indicate that (a). under basal conditions astrocytes released significantly more [(3)H]adenine nucleotides and [(3)H]adenosine than neurons, (b). OGD, NaCN and IAA conditions produced significant increases in [(3)H]adenosine release from neurons but not astrocytes, and (c) DPR blocked [(3)H]inosine release from both astrocytes and neurons but only blocked [(3)H]adenosine release from neurons. These data suggest that, in these experimental conditions, adenosine was formed by an intracellular pathway in neurons and then released via a nucleoside transporter. In contrast, adenine nucleotide release and extracellular metabolism to adenosine appeared to predominate in astrocytes.     

rBTI induces apoptosis in human solid tumor cell lines by loss in mitochondrial transmembrane potential and caspase activation

The molecular mechanisms and the possible effects of a recombinant buckwheat trypsin inhibitor (rBTI) on the induction of apoptosis in the human solid tumor cells (EC9706, HepG2 and HeLa) were investigated. An MTT assay showed that rBTI could specifically inhibit the growth of solid tumor cells in a dose- and time-dependent manner. Analysis by flow cytometry indicated that the apoptosis of several tumor cells increased after treatment with rBTI in range of 6.25–50 μg/ml. DNA electrophoresis analysis showed the ‘DNA ladder’, typical of apoptosis. rBTI-induced apoptosis was shown to involve Bax and Bak up-regulation, Bcl-2 and Bcl-xl down-regulation, release of cytochrome c from the mitochondria to the cytosol, activation of caspase-3 and -9 and disruption of the mitochondrial transmembrane potential (Δψ_m). The z-DEVD-fmk caspase-3 inhibitor significantly inhibited rBTI-induced apoptosis. We concluded that rBTI can induce the apoptosis in several types of human solid tumor cells and promotes apoptosis through the mitochondrial apoptotic pathway.     

Early loss of mitochondrial inner transmembrane potential in khat-induced cell death of primary normal human oral cells

Previous studies suggest the use of khat, a psychostimulant plant used by millions of people in Middle East and Africa, as risk factor for oral cancer. We previously reported that khat is able to induce adverse affects, as cell cycle arrest and apoptosis, in normal human oral cells cultured in vitro. This study further investigates the more specific role played by mitochondria in khat-induced cell death and the kinetics of the events involved in this process. Exposure of primary normal human oral keratinocytes and fibroblasts to khat extract resulted in a swift and sustained decrease of the mitochondrial inner transmembrane potential occurring within 0.5–1 h. Loss of mitochondrial membrane potential preceded all other biochemical and morphologic changes, and was associated with a significant decrease in cell survival. Subsequently, apoptosis-inducing factor was released from mitochondria into cytosol and relocated to nucleus. Cyclosporine A and bongkrekic acid delayed both the loss of mitochondrial inner transmembrane potential and the onset of cell death. This study describes a novel mechanism of khat-induced cell death in primary normal oral keratinocytes and fibroblasts involving an early pivotal effect on mitochondrial function and integrity.     

The metalloporphyrin FeTPPS but not by cyclosporin A antagonizes the interaction of peroxynitrate and hydrogen peroxide on cardiomyocyte cell death

The objective of this study was to determine whether the metalloporphyrin, 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrinato iron (III) chloride (FeTPPS), antagonized the effect of peroxynitrite, oxygen-free radicals, and the combination of the two, on cardiomyocyte cell viability. We further sought to compare the effects of FeTPPS to an inhibitor of the mitochondrial transmembrane permeability transition pores (PTP)—cyclosporin A. Cardiomyocytes from embryonic chick heart were treated with 3-morpholinosydnonimine (SIN-1), which decomposes to liberate NO and superoxide anion (O₂ ⁻) which in turn generates peroxynitrite. FeTPPS antagonized cell death induced by either SIN-1 or H₂O₂. The combination of H₂O₂ plus SIN-1 further enhanced the amount of cell death over SIN-1 alone. FeTPPS rescued cells from almost complete cell death with the combination of SIN-1 plus H₂O₂. SIN-1 induced cardiac protein nitration, including mitochondrial proteins as demonstrated by Western blotting with nitrotyrosine-specific antibodies. FeTPPS reduced cellular protein nitration. SIN-1-induced loss of mitochondrial transmembrane permeability transition pores potential was visualized with fluorescent dye staining and was reversed by FeTPPS. In contrast, the mitochondrial PTP blocker cyclosporin A did not alter SIN-1-induced cell death. In summary, these data demonstrate the enhanced cellular lethality of the combination of peroxynitrite and reactive oxygen species from hydrogen peroxide. A mitochondrial death pathway was implicated as nitration of mitochondrial proteins was induced by peroxynitrite that also induced a loss of ΔΨm that was prevented by FeTPPS. In contrast, cyclosporin did not antagonize the effects of SIN-1. The ability of FeTPPS to reduce reactive nitrogen-induced cell death, and protein nitration suggests that FeTPPS is a useful agent to maintain cell viability and is better than cyclosporin in this situation.     

Ethanol hyperpolarizes mitochondrial membrane potential and increases mitochondrial fraction in cultured mouse myocardial cells

Cultured mouse heart-derived myocardial and non-muscle cells were exposed to ethanol, stained with cell-permeant fluorescent vital probes, JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolyl-carbocyanine iodide) and oxidation-sensitive dihydrorhodamine 123, and analyzed by flow cytometry to elucidate ethanol-induced time-wise alterations in the mitochondrial membrane potential (ΔΨm) and the production of reactive oxygen species (ROS). Ethanol (50 and 200 mM) not only hyperpolarized ΔΨm of both types of cells but also dose-dependently increased ROS production at 24 h, although a 200-mM dose reduced the production until 3 h. These cell pathophysiological reactions suggest the depression of mitochondrial ATPase and mitochondrial respiratory chain. However, differences between these cells appeared after a 24-h exposure to 200 mM ethanol: the increase in ROS production was approximately twice as large for myocardial cells as for non-muscle cells; and the side-scatter parameter of light scattering significantly increased for myocardial cells, but not for non-muscle cells. All these myocyte-specific alterations indicate an increase in the mitochondrial fraction in a cell. This reaction might be a countermeasure against ethanol-induced dysfunction of mitochondrial respiration that is needed to meet the energy requirements of spontaneous myocardial contractions.     

Peripheral benzodiazepine receptor ligands: mitochondrial transmembrane potential depolarization and apoptosis induction in rat C6 glioma cells

The peripheral benzodiazepine receptor (PBR) is a component of a multiprotein complex, located at the contact site between the inner and outer mitochondrial membranes, which constitutes the mitochondrial permeability transition (MPT)-pore. The opening of the MPT-pore, leading to the transmembrane mitochondrial potential (DeltaPsi(m)) dissipation, is a critical event in the mechanism of apoptosis. In the present work, we investigated the ability of the specific PBR ligands, PK 11195 or Ro5-4864, to affect mitochondrial potential and to induce apoptotic cell death in rat C6 glioma cells. Both specific ligands inhibited cell survival in a dose- and time-dependent manner, as assessed by MTS conversion assay, whereas the non-site selective ligand Diazepam or the low-affinity benzodiazepine Clonazepam showed no significant effects. After cell exposure to PK 11195 or Ro5-4864 we evidenced typical alterations of apoptotic cell death such as DNA fragmentation and chromatin condensation assessed by flow cytometric and transmission electron microscopy (TEM) analysis, respectively. Activation of the "effector" caspase-3 confirmed the ability of specific PBR ligands to induce apoptosis. Moreover, PK 11195 and Ro5-4864 induced a decrease of DeltaPsi(m), as evidenced by JC-1 flow cytometry analysis. Our data demonstrate the pro-apoptotic effects of specific PBR ligands on rat C6 glioma cells.     

神经酰胺诱导结肠癌HT-29细胞凋亡与线粒体膜电位变化的关系

目的 探索神经酰胺(C2-ceramide,C2-cer)对人结肠癌HT-29细胞增殖、线粒体膜电位改变、细胞凋亡等的影响.方法 正常培养的HT-29细胞分为C2-cer处理组与非处理组,用MTT法、流式细胞仪等方法观察不同时间C2-cer对细胞增殖、线粒体膜电位改变、细胞凋亡等的影响.结果 加入C2-cer可引起HT-29细胞线粒体膜电位 (△Ψm)下降,细胞增殖受抑,并导致细胞凋亡.上述效应与C2-cer剂量以及作用时间相关.结论 C2-cer可导致HT-29细胞线粒体膜电位(△Ψm)下降,抑制细胞增殖,诱导细胞凋亡.     

Cholinergic-receptor-independent dysfunction of mitochondrial respiratory chain enzymes, reduced mitochondrial transmembrane potential and ATP depletion underlie necrotic cell death induced by the organophosphate poison mevinphos

Our current understanding of the nature of cell death that is associated with fatal organophosphate poisoning and the underlying cellular mechanisms is surprisingly limited. Taking advantage of the absence in an in vitro system of acetylcholinesterase, the pharmacological target of organophosphate compounds, the present study evaluated the hypothesis that the repertoire of cholinergic receptor-independent cellular events that underlie fatal organophosphate poisoning entails induction of mitochondrial dysfunction, followed by bioenergetic failure that leads to necrotic cell death because of ATP depletion. Pheochromocytoma PC12 cells incubated with the organophosphate pesticide mevinphos (0.4 or 4 μmol) for 1 or 3 h underwent a dose-related and time-dependent loss of cell viability that was not reversed by muscarinic (atropine) or nicotinic (mecamylamine) blockade. This was accompanied by depressed NADH cytochrome c reductase, succinate cytochrome c reductase or cytochrome c oxidase activity in the mitochondrial respiratory chain, reduced mitochondrial transmembrane potential, decreased ATP concentration, elevated ADP/ATP ratio, increased lactate dehydrogenase release and necrotic cell death. We conclude that Mev induces cholinergic receptor-independent necrotic cell death by depressing the activity of Complexes I to IV in the mitochondrial respiratory chain, eliciting reduction in mitochondrial transmembrane potential, depleting intracellular ATP contents and damaging cell membrane integrity.     

Nitrotyrosine attenuates the hemodynamic effects of adrenoceptor agonists in vivo: relevance to the pathophysiology of peroxynitrite

Peroxynitrite, which attenuates catecholamine-mediated hemodynamic responses in vivo, nitrates free tyrosine residues to form the specific product, 3-nitro- -tyrosine. The chemical structure of 3-nitro- -tyrosine is similar to that of the endogenous catecholamines. Therefore, 3-nitro- -tyrosine may interfere with catecholamine hemodynamic function in vivo. The hemodynamic responses produced by norepinephrine (1-4 μg/kg, i.v., n = 6), epinephrine (0.5-4 μg/kg, i.v., n = 7), phenylephrine (1-8 μg/kg, i.v., n = 5), and isoproterenol (100-400 ng/kg, i.v., n = 5) were attenuated, while the hemodynamic responses produced by arginine vasopressin (50-250 ng/kg; i.v., n = 5) were unaffected following the administration of 3-nitro- -tyrosine (2.5 μmol/kg, i.v.) in pentobarbital-anesthetized rats. These results demonstrate substantial and selective attenuation of the hemodynamic effects produced by - and β-adrenoceptor agonists, raising the possibility that 3-nitro- -tyrosine may play a role in the hemodynamic dysfunction associated with inflammatory conditions in which the formation of peroxynitrite is favored.     

Regulation of metal transporters by dietary iron,and the relationship between body iron levels and cadmium uptake

Iron (Fe) plays essential roles in biological processes, whereas cadmium (Cd) is a toxic and non-essential metal. Two metal transporters, divalent metal transporter 1 (DMT1) and metal transporter protein 1 (MTP1), are responsible for Fe transport in mammals. Here, we studied the effect of dietary Fe on the expression of these metal transporters in peripheral tissues, and the uptake by these tissues of Cd. Mice were fed an Fe-sufficient (FeS: 120 mg Fe/kg) or Fe-deficient (FeD: 2–6 mg Fe/kg) diet for 4 weeks. The total Fe levels in the body were evaluated by measuring tissue Fe concentrations. Tissue Cd concentrations were determined 24 h after the mice received a single oral dose of Cd. Animals fed a FeD diet showed depletion of body Fe levels and accumulated 2.8-fold higher levels of Cd than the FeS group. Quantitative real time RT-PCR revealed that whereas DMT1 and MTP1 were both ubiquitously expressed in all FeS peripheral tissues studied, DMT1 was highly expressed in brain, kidney, and testis, whereas MTP1 was highly expressed in liver and spleen. Depletion of the body Fe stores dramatically upregulated DMT1 and MTP1 mRNA expression in the duodenum as well as moderately upregulating their expression in several other peripheral tissues. The iron response element positive isoform of DMT1 was the most prominently upregulated isoform in the duodenum. Thus, DMT1 and MTP1 may play an important role in not only maintaining Fe levels but also facilitating the accumulation of Cd in the body of mammals.     

Mitochondrial membrane potential measurement of H9c2 cells grown in high-glucose and galactose-containing media does not provide additional predictivity towards mitochondrial assessment

Drug-induced mitochondrial toxicity is a contributing factor to many organ toxicities. The fact that some, but not all members of a particular drug class can induce mitochondrial dysfunction has necessitated the need for predictive screens within the drug development process. One of these screens is a cell viability assay done in two types of media, one containing high-glucose, the other, galactose. Since galactose-grown cells are more susceptible to mitochondrial toxicants than high-glucose-grown cells, this assay distinguishes compounds that cause toxicity primarily through mitochondrial targets from those that cause multifactorial toxicity. However, the assay does not show if compounds that cause multifactorial toxicity cause impairment on mitochondria. To address this problem, we investigated if multiplexing the assay with mitochondrial membrane potential measurements using the fluorescent dye, JC-1, could provide further information. We tested 28 drugs in the multiplexed assay and found that, although mitochondrial toxicants could be detected, no additional information was revealed about compounds that caused multifactorial toxicity. Hence, measurements with JC-1 did not provide additional information beyond what was detected using the cell viability assay. We conclude that even though the multiplexed assay is useful for HTS applications, it provides no additional value over the high-glucose-galactose cell viability assay.     

Novel action of the chalcone isoliquiritigenin as a cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor: potential therapy for cholera and polycystic kidney disease

Overstimulation of cAMP-activated Cl(-) secretion can cause secretory diarrhea. Isoliquiritigenin (ISLQ) is a plant-derived chalcone that has a wide range of biological activities. The present study thus aimed to investigate the effect of ISLQ on cAMP-activated Cl(-) secretion in human intestinal epithelium, especially the underlying mechanism and therapeutic application. Short-circuit current analysis of human intestinal epithelial (T84) cell monolayers revealed that ISLQ dose-dependently inhibited cAMP-activated Cl(-) secretion with an IC(50) of approximately 20 μM. ISLQ had no effect on either basal short-circuit current or Ca(2+)-activated Cl(-) secretion. Apical Cl(-) current analysis of T84 cell monolayers indicated that ISLQ blocked mainly the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels, but not other unidentified cAMP-dependent Cl(-) channels. ISLQ did not affect intracellular cAMP levels or cell viability. ISLQ completely abolished the cholera toxin-induced transepithelial Cl(-) secretion in T84 cells and reduced the cholera toxin-induced intestinal fluid secretion in mouse closed loop models by 90%. Similarly, ISLQ completely inhibited the cAMP-activated apical Cl(-) current across monolayers of Madin-Darby Canine Kidney (MDCK) cells and retarded cyst growth in MDCK cyst models by 90%. This study reveals a novel action of ISLQ as a potent CFTR inhibitor with therapeutic potential for treatment of cholera and polycystic kidney disease.     

阿霉素热化疗诱导A549细胞凋亡及线粒体跨膜电位的变化

目的 :探讨阿霉素 (adrimycin ,ADM)热化疗诱导人肺腺癌A5 49细胞凋亡及对线粒体跨膜电位(Δψm)的影响。 方法 :不同浓度的阿霉素作用于体外培养的A5 49细胞 ,4 2 .5℃作用 30min后 ,37℃继续培养 ,在不同时间内检测。用电镜、MTT法、流式细胞仪检测。结果 :阿霉素热化疗明显增强对A5 49细胞的抑制作用 ,细胞内阿霉素的浓度显著高于化疗组 (P <0 .0 1) ;阿霉素浓度为 1.0 ,2 .0mg·L-1时 ,热化组与化疗组比较 ,凋亡率增高 ,线粒体膜电位下降 (P <0 .0 1)。结论 :线粒体跨膜电位下降可能是ADM热化疗诱导A5 49细胞凋亡的关键     

大肠癌线粒体DNA诱导NIH3T3细胞D-环突变的作用与机制

目的观察突变的大肠癌细胞线粒体DNA(mtDNA)转导NIH3T3细胞后转染细胞mtDNA D-环突变特性。方法通过脂质体法(Lipofection2000TM)将大肠癌细胞突变的mtDNA真核表达载体转染NIH3T3细胞,利用G418抗性筛选克隆细胞;用PCR法检测转染细胞线粒体突变情况。结果突变mtDNA导致转染细胞mtDNA的突变和多态性变化。结论突变的大肠癌mtDNA可致NIH3T3细胞mtDNA位点变化,但具体的机制和过程有待于进一步研究。     

Role of oxidative stress, mitochondrial membrane potential, and calcium homeostasis in human lymphocyte death induced by nickel carbonate hydroxide in vitro

When isolated human lymphocytes were treated in vitro with various concentrations of soluble form of nickel carbonate hydroxide (NiCH) (0–1 mM), at 37°C for 4 h, both concentration- and time-dependent effects of NiCH on lymphocyte death were observed. Increased generation of hydrogen peroxide (H₂O₂), superoxide anion (O ₂ ⁻ ), depletion of both no protein (NP-) and protein (P-) sulfhydryl (SH) contents and lipid peroxidation (LPO) were induced by NiCH. Pretreatment of lymphocytes with either catalase (H₂O₂ scavenger), or deferoxamine (DFO) (iron chelator), or excess glutathione (GSH) (an antioxidant) not only significantly reduced the NiCH-induced generation of H₂O₂ and LPO, but also increased the NP-SH and P-SH contents initially reduced by NiCH. NiCH-induced generation of excess O ₂ ⁻ but not excess LPO was significantly reduced by pretreatment with superoxide dismutase (SOD). NiCH-induced lymphocyte death was significantly prevented by pre-treatment with either catalase, or dimethylthiourea/mannitol (hydroxyl radical scavengers), or DFO, or excess GSH/N-acetylcysteine. NiCH-induced lymphocyte death was also significantly prevented by pretreatment with excess SOD. Thus, various types of oxidative stresses play an important role in NiCH-induced lymphocyte death. Cotreatment with cyclosporin A (a specific inhibitor of alteration in mitochondrial membrane potential (ΔΨ_m) not only inhibited NiCH-induced alteration in ΔΨ_m, but also significantly prevented Ni-compound-induced lymphocyte death. Furthermore, NiCH-induced destabilization of cellular calcium homeostasis. As such, NiCH-induced lymphocyte death was significantly prevented by modulating intracellular calcium fluxes such as Ca²⁺ channel blockers and intracellular Ca²⁺ antagonist. Thus, the mechanism of NiCH (soluble form)-induced activation of lymphocyte death signalling pathways involves not only the excess generation of different types of oxidative stress, but also the induction of alteration in ΔΨ_m and destabilization of cellular calcium homeostasis as well.     

The effects of 3, 4 or 5 amino salicylic acids on manganese-induced neuronal death: ER stress and mitochondrial complexes

This study was designed to investigate the mechanisms that are associated with manganese (Mn) toxicity. In addition, the association between Mn toxicity and 3, 4, 5 amino salicylic acid (ASA), anti-oxidants, including N-acetyl cysteine (NAC), was examined by dopaminergic cell line, SK-M-NC. Our studies showed that Mn influenced the mitochondria dysfunction and endoplasmic reticulum stress (ER stress). It reduced the mitochondria complex I activity but did not affect the complex II, III, or IV activities. The presence of 3, 4, 5 ASA protected against Mn-induced-apoptosis, as did NAC. However, the salicylate analogues and the antioxidants did not mediate ER stress in this model. The salicylate analogues reduced reactive oxygen species (ROS) and reversed the deficient mitochondrial membrane potential that was induced by Mn. Taken together, the 3, 4, 5 ASA worked in a similar way, regulating the Mn-induced mitochondrial dysfunction and protecting cells.     

Adenosine alters the vascular effects of a diacylglycerol analogue and polymyxin B

Endothelium-denuded rat aorta rings were used to study the possible relationship between protein kinase C and the mechanism of adenosine-induced smooth muscle relaxation. Adenosine (5 × 10⁻⁴M) partially relaxed the aortic rings contracted by either a depolarising amount of KCl (4 × 10⁻² M) or activation of protein kinase C with l-oleoyl-2- acetyl-sn-glycerol (10⁻⁶ M). The same amount of adenosine blocked the further relaxation obtained in the presence of polymyxin B (5 × 10⁻⁵ M), a protein kinase C blocking agent. These results suggest a possible interaction in vascular smooth muscle between adenosine and protein kinase C.