Neuronal Cell Death and Reactive Oxygen Species

1. We have investigated the role of reactive oxygen species (ROS) in cell death induced by ischemia or application of the excitatory amino acid agonist, N-methyl-D-aspartate (NMDA) or kainate (KA), in acutely isolated rat cerebellar granule cell neurons, studied by flow cytometry. Various fluorescent dyes were used to monitor intracellular calcium concentration, ROS concentration, membrane potential, and viability in acutely dissociated neurons subjected to ischemia and reoxygenation alone, NMDA or kainate alone, and ischemia and reoxygenation plus NMDA or kainate.2. With ischemia followed by reoxygenation, ROS concentrations rose slightly and there was only a modest increase in cell death after 60 min.3. When NMDA or kainate alone was applied to the cells there was a large increase in ROS and in intracellular calcium concentration but only a small loss of cellular viability. However, when NMDA or kainate was applied during the reoxygenation period there was a large loss of viability, accompanied by membrane depolarization, but the elevations of ROS and intracellular calcium concentration were not greater than seen with the excitatory amino acids alone.4. These observations indicate that other factors beyond ROS and intracellular calcium concentration contribute to cell death in cerebellar granule cell neurons.     

Generation of Reactive Oxygen Species from Hinokitiol under Near-UV Irradiation

Near-UV irradiation caused the decomposition of hinokitiol in an aqueous solution. During the photochemical reaction, the distinct electron spin resonance signal characteristic of the adduct of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) with the hydroxyl radical was accompanied by small signals corresponding to the adduct of DMPO with the superoxide anion radical. More than 95% of Escherichia coli cells were killed by the incubation with hinokitiol under near-UV irradiation by BLB fluorescent lamps. These results indicated the generation of reactive oxygen species during photochemical reaction of hinokitiol under near-UV irradiation.     

Catalytic Coupling of Oxidative Phosphorylation,ATP Demand,and Reactive Oxygen Species Generation

Competing models of mitochondrial energy metabolism in the heart are highly disputed. In addition, the mechanisms of reactive oxygen species (ROS) production and scavenging are not well understood. To deepen our understanding of these processes, a computer model was developed to integrate the biophysical processes of oxidative phosphorylation and ROS generation. The model was calibrated with experimental data obtained from isolated rat heart mitochondria subjected to physiological conditions and workloads. Model simulations show that changes in the quinone pool redox state are responsible for the apparent inorganic phosphate activation of complex III. Model simulations predict that complex III is responsible for more ROS production during physiological working conditions relative to complex I. However, this relationship is reversed under pathological conditions. Finally, model analysis reveals how a highly reduced quinone pool caused by elevated levels of succinate is likely responsible for the burst of ROS seen during reperfusion after ischemia.     

叶绿体中活性氧的产生和清除机制

正常情况下植物细胞内活性氧（reactive oxygen species ROS）的产生和清除是平衡的,但是,一旦植物遭受环境胁迫,ROS的积累超过抗氧化剂防护系统清除能力,就会产生氧胁迫损伤细胞。由于叶绿体作为光合作用的场所与其他细胞器相比更易遭受氧化胁迫的伤害。因此,叶绿体进化了更强的防御机制调控电子传递链的氧化还原平衡及叶绿体基质中的氧化还原状态。活性氧具有双重效应．高浓度的活性氧对植物细胞有很强的毒害作用,低浓度时可充当信号分子参与植物的某些防卫反应过程,本文就叶绿体中活性氧的产生（三线态叶绿素、PSI和PSI I电子传递链）、网络清除（抗氧化剂,SOD,As—Glu循环系统,硫氧还蛋白）机制以及功能作用进行了综述。     

信号配体诱导的活性氧生成

活性氧(reactiveoxygenspecies,ROS)是生物体内一类活性含氧化合物的总称,主要包括超氧阴离子、羟自由基和过氧化氢等。细胞内有多种部位能生成ROS,主要包括线粒体、内质网、NADPH氧化酶复合体、脂氧合酶系、环氧合酶系等。静息条件下,细胞内ROS的水平被控制在很低的范围。而在细胞受到各种生理或病理因素作用时,当多种细胞外信号分子作用于其膜受体,ROS生成可以受到受体活化的诱导而“有目的”地快速增加,从而作为细胞内信号分子参与细胞增殖,分化和凋亡等各种细胞行为。     

Reactive Oxygen Species from Human Astrocytes Induced Functional Impairment and Oxidative Damage

Reactive oxygen species (ROS) have been shown to be a contributor to aging and disease. ROS also serve as a trigger switch for signaling cascades leading to corresponding cellular and molecular events. In the central nervous system (CNS), microglial cells are likely the main source of ROS production. However, activated astrocytes also appear to be capable of generating ROS. In this study we investigated ROS production in human astrocytes stimulated with interleukin (IL)-1β and interferon (IFN)-γ and its potential harmful effects. Although IFN-γ alone had no effect, it potentiated IL-1β-induced ROS production in a time-dependent manner. One of the sources of ROS in IL-1β-activated astrocytes was from increased superoxide production in mitochondria accompanied by enhanced manganese superoxide dismutase and inhibited catalase expression. NADPH oxidase (NOX) may also contribute to ROS production as astrocytes express NOX isoforms. Glutamate uptake, which represents one of the most important methods of astrocytes to prevent excitotoxicity, was down-regulated in IL-1β-activated astrocytes, and was further suppressed in the presence of IFN-γ; IFN-γ itself exerted minimal effect. Elevated levels of 8-isoprostane in IL-1β ± IFN-γ-activated human astrocytes indicate downstream lipid peroxidation. Pretreatment with diphenyleneiodonium abolished the IL-1β ± IFN-γ-induced ROS production, restored glutamate uptake function and reduced 8-isoprostane to near control levels suggesting that ROS contributes to the dysfunction of activated astrocytes. These results support the notion that dampening activated human astrocytes to maintain the redox homeostasis is vital to preserve their neuroprotective potential in the CNS.     

Ca2+ and Reactive Oxygen Species in Staurosporine-Induced Neuronal Apoptosis

Abstract: Staurosporine (0.03–0.5 µ M ) induced a dose-dependent, apoptotic degeneration in cultured rat hippocampal neurons that was sensitive to 24-h pretreatments with the protein synthesis inhibitor cycloheximide (1 µ M ) or the cell cycle inhibitor mimosine (100 µ M ). To investigate the role of Ca²⁺ and reactive oxygen species in staurosporine-induced neuronal apoptosis, we overexpressed calbindin D_28K, a Ca²⁺ binding protein, and Cu/Zn superoxide dismutase, an antioxidative enzyme, in the hippocampal neurons using adenovirus-mediated gene transfer. Infection of the cultures with the recombinant adenoviruses (100 multiplicity of infection) resulted in a stable expression of the respective proteins assessed 48 h later. Overexpression of both calbindin D_28K and Cu/Zn superoxide dismutase significantly reduced staurosporine neurotoxicity compared with control cultures infected with a β-galactosidase overexpressing adenovirus. Staurosporine-induced neuronal apoptosis was also significantly reduced when the culture medium was supplemented with 10 or 30 m M K⁺, suggesting that Ca²⁺ influx via voltage-sensitive Ca²⁺ channels reduces this apoptotic cell death. In contrast, neither the glutamate receptor agonist NMDA (1–10 µ M ) nor the NMDA receptor antagonist dizocilpine (MK-801; 1 µ M ) was able to reduce staurosporine neurotoxicity. Cultures treated with the antioxidants U-74500A (1–10 µ M ) and N -acetylcysteine (100 µ M ) also demonstrated reduced staurosporine neurotoxicity. These results suggest a fundamental role for both Ca²⁺ and reactive oxygen species in staurosporine-induced neuronal apoptosis.     

Catechins Induce Oxidative Damage to Cellular and Isolated DNA through the Generation of Reactive Oxygen Species

Green tea catechins have antimutagenic and anticarcinogenic activities. On the other hand, several epidemiological studies have indicated significant positive relationship between green tea consumption and cancer. Catechins enhance colon carcinogenesis in rats initiated with chemical carcinogen. To clarify the mechanism underlying the potential carcinogenicity, we investigated the DNA-damaging ability of catechins in human cultured cells. Catechin increased the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a characteristic oxidative DNA lesion, in human leukemia cell line HL-60 but not in HP100, a hydrogen peroxide (H₂O₂)-resistant cell line derived from HL-60. The catechin-induced formation of 8-oxodG in HL-60 cells significantly decreased by bathocuproine. Furthermore, we investigated DNA damage and its site-specificity induced by catechins, using ₃₂P-labeled DNA fragments. Catechin and epicatechin induced extensive DNA damage in the presence of Cu(II). Catechin caused piperidine-labile sites at thymine and cytosine residues in the presence of Cu(II). Catalase and bathocuproine inhibited the DNA damage, indicating the involvement of H₂O₂ and Cu(I). NADH enhanced catechins plus Cu(II)-induced 8-oxodG formation in calf thymus DNA, suggesting the redox cycle between catechins and their corresponding quinones, the oxidized forms of catechins. The DNA-damaging ability of epicatechin is stronger than that of catechin, possibly due to the greater turnover frequency of the redox cycle. The difference in their redox properties could be explained by their redox potentials estimated form an ab initio molecular orbital calculation. The present study demonstrated that catechins could induce metal-dependent H₂O₂ generation during the redox reactions and subsequently damage to cellular and isolated DNA. Therefore, it is reasonably considered that green tea catechins may have the dual function of anticarcinogenic and carcinogenic potentials.     

Increased Reactive Oxygen Species Formation and Oxidative Stress in Rheumatoid Arthritis

BackgroundRheumatoid arthritis (RA) is an autoimmune inflammatory disorder. Highly reactive oxygen free radicals are believed to be involved in the pathogenesis of the disease. In this study, RA patients were sub-grouped depending upon the presence or absence of rheumatoid factor, disease activity score and disease duration. RA Patients (120) and healthy controls (53) were evaluated for the oxidant—antioxidant status by monitoring ROS production, biomarkers of lipid peroxidation, protein oxidation and DNA damage. The level of various enzymatic and non-enzymatic antioxidants was also monitored. Correlation analysis was also performed for analysing the association between ROS and various other parameters.MethodsIntracellular ROS formation, lipid peroxidation (MDA level), protein oxidation (carbonyl level and thiol level) and DNA damage were detected in the blood of RA patients. Antioxidant status was evaluated by FRAP assay, DPPH reduction assay and enzymatic (SOD, catalase, GST, GR) and non-enzymatic (vitamin C and GSH) antioxidants.ResultsRA patients showed a higher ROS production, increased lipid peroxidation, protein oxidation and DNA damage. A significant decline in the ferric reducing ability, DPPH radical quenching ability and the levels of antioxidants has also been observed. Significant correlation has been found between ROS and various other parameters studied.ConclusionRA patients showed a marked increase in ROS formation, lipid peroxidation, protein oxidation, DNA damage and decrease in the activity of antioxidant defence system leading to oxidative stress which may contribute to tissue damage and hence to the chronicity of the disease.     

Oxygen Sensitivity of Mitochondrial Reactive Oxygen Species Generation Depends on Metabolic Conditions

The mitochondrial generation of reactive oxygen species (ROS) plays a central role in many cell signaling pathways, but debate still surrounds its regulation by factors, such as substrate availability, [O₂] and metabolic state. Previously, we showed that in isolated mitochondria respiring on succinate, ROS generation was a hyperbolic function of [O₂]. In the current study, we used a wide variety of substrates and inhibitors to probe the O₂ sensitivity of mitochondrial ROS generation under different metabolic conditions. From such data, the apparent K_m for O₂ of putative ROS-generating sites within mitochondria was estimated as follows: 0.2, 0.9, 2.0, and 5.0 μm O₂ for the complex I flavin site, complex I electron backflow, complex III Q_O site, and electron transfer flavoprotein quinone oxidoreductase of β-oxidation, respectively. Differential effects of respiratory inhibitors on ROS generation were also observed at varying [O₂]. Based on these data, we hypothesize that at physiological [O₂], complex I is a significant source of ROS, whereas the electron transfer flavoprotein quinone oxidoreductase may only contribute to ROS generation at very high [O₂]. Furthermore, we suggest that previous discrepancies in the assignment of effects of inhibitors on ROS may be due to differences in experimental [O₂]. Finally, the data set (see supplemental material) may be useful in the mathematical modeling of mitochondrial metabolism.The production of reactive oxygen species (ROS)² by mitochondria has been implicated in numerous disease states, including but not limited to sepsis, solid state tumor survival, and diabetes (1). In addition, mitochondrial ROS (mtROS) play key roles in cell signaling (reviewed in Refs. 2 and 3). There exist within mitochondria several sites for the generation of ROS, with the most widely studied being complexes I and III of the electron transport chain (ETC). However, there is currently some debate regarding the relative contribution of these complexes to overall ROS production (4–9) and the factors that may alter this distribution. One such factor considered herein is [O₂]. Estimates of physiological [O₂] within tissues (i.e. interstitial [O₂]) range from 37 down to 6 μm at 5–40 μm away from a blood vessel (10). More recently, EPR oximetry has estimated tissue [O₂] to be in the 12–60 μm range (11). In addition, elegant studies with hepatocytes have shown that O₂ gradients exist within cells, such that an extracellular [O₂] of 6–10 μm yields an [O₂] of ∼5 μm close to the plasma membrane, dropping to 1–2 μm close to mitochondria deep within the cell (12). In cardiomyocytes, at an extracellular [O₂] of 29 μm, intracellular [O₂] varied in the range 6–25 μm (13). Clearly, different tissues consume O₂ at different rates, so these gradients can vary considerably between tissue and cell types.By definition, the generation of reactive oxygen species by any mechanism, is an O₂-dependent process. However, measurements in intact cells have indicated that mtROS generation increases at lower O₂ levels (1–5% O₂) (14). Proponents of an increase in mtROS in response to hypoxia suggest that under such conditions, reduction of the ETC results in increased leakage of electrons to O₂ at the Q_O site of complex III (14). Such a model posits that increased hypoxic ROS is a mitochondria-autonomous signaling mechanism (i.e. it is an inherent property of the mitochondrial ETC). Therefore, mtROS generation should increase in hypoxia regardless of the experimental system being studied, including isolated mitochondria. In contrast to this hypothesis, we and others have demonstrated that ROS generation by mitochondria is a positive function of [O₂] across a wide range of values (0.1–1000 μm O₂) (15–18), suggesting that signaling mechanisms external to mitochondria may be required to facilitate the increased hypoxic mtROS production observed in cells.One limitation of our previous work (15) was that only a single respiratory condition was studied, namely succinate as respiratory substrate (feeding electrons into complex II) plus rotenone to inhibit backflow of electrons through complex I (5, 7). The possibility exists that under different metabolic conditions, which may lead to differential redox states between the cytochromes in the ETC (19, 20), ROS generation may exhibit a different response to [O₂]. Thus, in the current study, we examined the response of mtROS generation to [O₂] under 11 different conditions, using a variety of respiratory substrates and inhibitors (for a thorough review of electron entry points to the ETC under various substrate/inhibitor combinations, see Ref. 21). Fig. 1 shows a schematic of the mitochondrial ETC, highlighting sites of electron entry resulting from various substrates, binding sites of inhibitors, and major sites of ROS generation. Fig. 2 shows the specific details of each experimental condition, indicating the predicted sites of ROS generation resulting from the use of each substrate/inhibitor combination. The legend to Fig. 2 provides an explanation of each condition.Open in a separate windowFIGURE 1.Mitochondrial pathways of electron flow resulting from the substrates and inhibitors used in this study. Substrates used were glutamate/malate (which generates NADH via the tricarboxylic acid cycle, feeding into complex I), succinate (which feeds electrons directly into complex II), and palmitoyl-carnitine (which feeds electrons into the ETC via acyl-CoA dehydrogenase as well as through the β-oxidation pathway). (For a more thorough explanation, refer to Ref. 21.) Inhibitors used were rotenone (which inhibits at the downstream Q binding site of complex I (9)), malonate (a competitive inhibitor of complex II (25, 26)), and antimycin A (a complex III inhibitor that prevents electron flow to the Q_I site of complex III, thus stabilizing QH^˙ at the Q_O site (6, 28)).Open in a separate windowFIGURE 2.Pathways of electron flow for the substrate/inhibitor combinations used in conditions A–L. Each panel includes the respective maximal respiration rate (VO_{2 max}; nmol of O₂/min/mg of protein) measured under each condition. A, glutamate/malate/malonate. Electrons enter through complex I, whereas electron entry at complex II is inhibited by malonate. ROS generation occurs at the FMN site of complex I as well as the Q_O site of complex III. B, glutamate/malate/malonate/rotenone. Electrons enter through complex I. Electron passage through complex I is inhibited by rotenone binding at the downstream Q site, resulting in maximal ROS production at the FMN site of complex I. ROS production at the Q_O site of complex III is prevented due to no electrons reaching the complex from either complexes I or II, both of which are inhibited. C, glutamate/malate/malonate/antimycin A. Electrons enter through complex I only, since complex II is blocked. Flow of electrons is inhibited by the complex III inhibitor antimycin A, resulting in ROS production at the Q_O site of complex III, as well as the FMN site of complex I. D, succinate. Electrons enter at complex II. ROS is generated by the flow of electrons though the Q_O site of complex III as well as the backflow of electrons through complex I. E, succinate/rotenone. Electrons enter at complex II, and ROS is generated at the Q_O site of complex III, because rotenone is present to inhibit backflow of electrons through complex I. F, succinate/antimycin A. Electrons enter through complex II. ROS is generated at both complex I via backflow and complex III Q_O, with an increased rate at the latter due to inhibition by antimycin A. G, succinate/rotenone/antimycin A. Electrons enter through complex II. Backflow of electrons through complex I is inhibited by rotenone, whereas ROS generation at complex III Q_O is augmented due to the presence of antimycin A. H, glutamate/malate/succinate. Electrons enter at both complexes I and II. ROS is generated from the complex I FMN site and the complex III Q_O site. J, glutamate/malate/succinate/antimycin A. Electrons enter at complexes I and II. ROS generation occurs at the complex I FMN and is augmented at the complex III Q_O site by antimycin A. K, palmitoyl-carnitine. Electrons enter at the ETFQOR. ROS is generated at the ETFQOR as well as complex I via backflow and at the complex III Q_O site. L, palmitoyl-carnitine/rotenone. Electron entry is at the ETFQOR. ROS is generated at the ETFQOR as well as at the complex III Q_O site, whereas ROS due to complex I backflow is blocked by rotenone. Glu, glutamate; Mal, malate; Suc, succinate; PC, palmitoyl-carnitine; Rot, rotenone; AntiA, antimycin A; Malon, malonate.The results of these studies indicated that although ROS generation under all experimental conditions exhibited the same overall response to [O₂] (i.e. hyperbolic, with decreased ROS at low [O₂]), the apparent K_m for O₂ varied widely between metabolic states.     

Identification of Possible Reactive Oxygen Species Involved in Ultraviolet Radiation-Induced Oxidative DNA Damage

We have previously demonstrated that each region of the ultraviolet (UV) spectrum (UVA, UVB, and UVC) induces the formation of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) in purified calf thymus DNA and HeLa cells in a fluence-dependent manner. In the present study, we further characterize the possible reactive oxygen species (ROS) that are involved in the induction of 8-oxodGuo by UV radiation. Sodium azide, a singlet oxygen (¹O₂) scavenger though its quenching effect on HO· was also reported, inhibited 8-oxodGuo production in calf thymus DNA exposed to UVA, UVB, or UVC in a concentration-dependent fashion with maximal quenching effect of over 90% at a concentration of 10 mM. Catalase, at a concentration of 50 U/ml, reduced the yields of UVA- and UVB-induced 8-oxodGuo formation by approximately 50%, but had little effect on UVC-induced 8-oxodGuo production. In contrast, 50 U/ml of superoxide dismutase (SOD) did not affect induction of 8-oxodGuo by any portion of the UV spectrum. Hydroxyl radical (HO·) scavengers mannitol and dimethylsulfoxide (DMSO) moderately reduced the levels of 8-oxodGuo induced by UVA and UVB, but not those by UVC. Instead, mannitol and DMSO enhanced the formation of 8-oxodGuo induced by UVC. These results suggest that certain types of ROS are involved in UV-induced 8-oxodGuo formation with ¹O₂ playing the predominant role throughout the UV spectrum. Except for UVC, other ROS such as hydrogen peroxide (H₂O₂) and HO· may also be involved in UVA- and UVB-induced oxidative DNA damage. Superoxide anion appears not to participate in UV-induced oxidation of guanosine in calf thymus DNA, as SOD did not display any quenching effects.     

Oxygen Toxicity Induces Apoptosis in Neuronal Cells

1. A high oxygen atmosphere induced apoptosis in cultured neuronal cells including PC12 cells and rat embryonic cortical, hippocampal, and basal forebrain neurons associated with DNA fragmentation and nuclear condensation.2. The sensitivity of CNS neurons to a high-oxygen atmosphere was the following order; cortex > basal forebrain > hippocampus.3. Cycloheximide and actinomycin-D inhibited the apoptosis, indicating that it depends on new macromolecular synthesis. In contrast, cultured postnatal CNS neurons were resistant to oxidative stress.4. Neurotrophic factors such as nerve growth factor (NGF), fibroblast growth factor (FGF), and epidermal growth factor (EGF) blocked the apoptosis induced by a high-oxygen atmosphere.     

植物活性氧的产生及其作用和危害

活性氧(ROS)是一类由O2转化而来的自由基或具有高反应活性的离子或分子。植物消耗的O2约有1%在叶绿体、线粒体、过氧化物酶体等多种亚细胞单位中被转化成了ROS。ROS有益或有害取决于它在植物体内的浓度。低浓度的ROS作为第二信使能在植物细胞信号转导途径中介导多种应答反应,高浓度的ROS则引起生物大分子的氧化损伤甚至细胞死亡。植物体内ROS产生和清除之间的平衡十分重要,并由一套有效的酶促和非酶促抗氧化系统来监控。该文主要系统介绍了植物ROS的种类、产生部位、在信号转导中的作用及其对植物细胞造成的主要伤害等方面的研究进展,为利用基因工程手段来提高植物对环境胁迫的抗性提供信息和思路。     

气孔运动中的活性氧信号

大量研究证明活性氧(ROS)在气孔运动中起信号分子的作用。保卫细胞中ROS的产生依赖于特定的酶, 其中NADPH氧化酶组分RBOH已得到深入研究, 并已证实其参与生物与非生物胁迫反应。植物激素包括脱落酸(ABA)、水杨酸(SA)、乙烯、生长素及细胞分裂素等, 它们均通过ROS的介导来调控气孔运动。生物胁迫(如毒性细菌和真菌)也会调控气孔运动。ROS参与这些调控过程。保卫细胞中存在多层次对ROS产生及其作用的调节, 抗氧化活性物质和ROS敏感蛋白(如蛋白激酶和磷酸酶)均可传递ROS信号并调节气孔运动。ROS对离子通道调节的证据也越来越多。保卫细胞由于可通过ROS整合复杂的信号途径, 已成为研究植物ROS信号转导过程的良好模式系统。     

Generation of Reactive Oxygen Species by Mitochondrial Complex I: Implications in Neurodegeneration

Mitochondrial Complex I [NADH Coenzyme Q (CoQ) oxidoreductase] is the least understood of respiratory complexes. In this review we emphasize some novel findings on this enzyme that are of relevance to the pathogenesis of neurodegenerative diseases. Besides CoQ, also oxygen may be an electron acceptor from the enzyme, with generation of superoxide radical in the mitochondrial matrix. The site of superoxide generation is debated: we present evidence based on the rational use of several inhibitors that the one-electron donor to oxygen is an iron-sulphur cluster, presumably N2. On this assumption we present a novel mechanism of electron transfer to the acceptor, CoQ. Complex I is deeply involved in pathological changes, including neurodegeneration. Complex I changes are involved in common neurological diseases of the adult and old ages. Mitochondrial cytopathies due to mutations of either nuclear or mitochondrial DNA may represent a useful model of neurodegeneration. In this review we discuss Parkinson’s disease, where the pathogenic involvement of Complex I is better understood; the accumulated evidence on the mode of action of Complex I inhibitors and their effect on oxygen radical generation is discussed in terms of the aetiology and pathogenesis of the disease. Special issue article in honor of Dr. Anna Maria Giuffrida-Stella.     

气孔运动中的活性氧信号

大量研究证明活性氧(ROS)在气孔运动中起信号分子的作用。保卫细胞中ROS的产生依赖于特定的酶,其中NADPH氧化酶组分RBOH已得到深入研究,并已证实其参与生物与非生物胁迫反应。植物激素包括脱落酸(ABA)、水杨酸(SA)、乙烯、生长素及细胞分裂素等,它们均通过ROS的介导来调控气孔运动。生物胁迫(如毒性细菌和真菌)也会调控气孔运动。ROS参与这些调控过程。保卫细胞中存在多层次对ROS产生及其作用的调节,抗氧化活性物质和ROS敏感蛋白(如蛋白激酶和磷酸酶)均可传递ROS信号并调节气孔运动。ROS对离子通道调节的证据也越来越多。保卫细胞由于可通过ROS整合复杂的信号途径,已成为研究植物ROS信号转导过程的良好模式系统。