Plasma membrane Ca^(2+)-ATPases in the nervous system during development and ageing

Calcium signaling is used by neurons to control a variety of functions,including cellular differentiation,synaptic maturation,neurotransmitter release,intracellular signaling and cell death.This review focuses on one of the most important Ca2+regulators in the cell,the plasma membrane Ca2+-ATPase(PMCA),which has a high affinity for Ca2+and is widely expressed in brain.The ontogeny of PMCA isoforms,linked to specific requirements of Ca2+ during development of different brain areas,is addressed, as well as their function in the adult tissue.This is based on the high diversity of variants in the PMCA family in brain,which show particular kinetic differences possibly related to specific localizations and functions of the cell. Conversely,alterations in the activity of PMCAs could lead to changes in Ca2+homeostasis and,consequently,to neural dysfunction.The involvement of PMCA isoforms in certain neuropathologies and in brain ageing is also discussed.

Plasma membrane Ca^(2+)-ATPases:Targets of oxidative stress in brain aging and neurodegeneration

The plasma membrane Ca2+-ATPase(PMCA)pumps play an important role in the maintenance of precise levels of intracellular Ca2+[Ca2+]i,essential to the functioning of neurons.In this article,we review evidence showing age-related changes of the PMCAs in synaptic plasma membranes(SPMs).PMCA activity and protein levels in SPMs diminish progressively with increasing age. The PMCAs are very sensitive to oxidative stress and undergo functional and structural changes when exposed to oxidants of physiological relevance.The major signatures of oxidative modification in the PMCAs are rapid inactivation,conformational changes,aggregation, internalization from the plasma membrane and proteolytic degradation.PMCA proteolysis appears to be mediated by both calpains and caspases.The predominance of one proteolytic pathway vs the other,the ensuing pattern of PMCA degradation and its consequence on pump activity depends largely on the type of insult,its intensity and duration.Experimental reduction of PMCA expression not only alters the dynamics of cellular Ca2+ handling but also has a myriad of downstream conse-quences on various aspects of cell function,indicating a broad role of these pumps.Age-and oxidation-related down-regulation of the PMCAs may play an important role in compromised neuronal function in the aging brain and its several-fold increased susceptibility to neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease,and stroke.Therapeutic approaches that protect the PMCAs and stabilize[Ca2+]i homeostasis may be capable of slowing and/or preventing neuronal degeneration.The PMCAs are therefore emerging as a new class of drug targets for therapeutic interventions in various chronic degenerative disorders.

Effects of salinity on activities of H^+-ATPase, H^+-PPase and membrane lipid composition in plasma membrane and tonoplast vesicles isolated from soybean(Glycine max L.) seedlings

The effects of NaCl stress on the H +-ATPase, H +-PPase activity and lipid composition of plasma membrane(PM) and tonoplast(TP) vesicles isolated from roots and leaves of two soybean cultivars(Glycine max L.) differing in salt tolerance(Wenfeng7, salt-tolerant; Union, salt-sensitive) were investigated. When Wenfeng7 was treated with 0.3%(W/V) NaCl for 3 d, the H +-ATPase activities in PM and TP from roots and leaves exhibited a reduction and an enhancement, respectively. The H +-PPase activity in TP from roots also increased. Similar effects were not observed in roots of Union. In addition, the increases of phospholipid content and ratios of phospholipid to galactolipid in PM and TP from roots and leaves of Wenfeng7 may also change membrane permeability and hence affect salt tolerance.

Changes of plasma membrane ATPase activity, membrane potential and transmembrane proton gradient in Kandelia candel and Avicennia marina seedlings with various salinities

The salt-secreting mangrove, Avicennia marina, and non-salt-secreting mangrove, Kandelia candel were cultivated in sand with various salinities(0‰, 10‰, 20‰, 30‰, 40‰) for 60 d. Plasma membrane vesicles of high-purity in leaves and roots of A.marina and K. candel seedlings were obtained by two-phase partitioning. The function of the plasma membranes, the activity of ATPase, membrane potential and transmembrane proton gradient, at various salinities were investigated. The results showed that within a certain range of salinity(A. marina and roots of K. candel: 0—30‰; leaves of K.candel: 0—20‰), the activity of ATPase increased with increasing salinity, while high salinity(above 30‰ or 20‰) inhibited ATPase activity. In comparison with A. marina, K. candel appeared to be more sensitive to salinity. The dynamics of membrane potential and transmembrane proton gradient in leaves and roots of A. marina and K. candel seedlings were similar to that of ATPase. When treated directly by NaCl all the indexes were inhibited markedly: there was a little increase within 0—10‰(K. candel) or 0—20‰(A. marina) followed by sharp declining. It indicated that the structure and function of plasma membrane was damaged severely.

Plasma membrane calcium ATPase proteins as novel regulators of signal transduction pathways

Emerging evidence suggests that plasma membrane calcium ATPases (PMCAs) play a key role as regulators of calcium-triggered signal transduction pathways via interaction with partner proteins. PMCAs regulate these pathways by targeting specific proteins to cellular sub-domains where the levels of intracellular freecalcium are kept low by the calcium ejection properties of PMCAs. According to this model, PMCAs have been shown to interact functionally with the calcium-sensitive proteins neuronal nitric oxide synthase, calmodulindependent serine protein kinase, calcineurin and endothelial nitric oxidase synthase. Transgenic animals with altered expression of PMCAs are being used to evaluate the physiological significance of these interactions. To date, PMCA interactions with calcium-dependent partner proteins have been demonstrated to play a crucial role in the pathophysiology of the cardiovascular system via regulation of the nitric oxide and calcineurin/nuclear factor of activated T cells pathways. This new evidence suggests that PMCAs play a more sophisticated role than the mere ejection of calcium from the cells, by acting as modulators of signaling transduction pathways.

Changes of Plasma Membrane H^+-ATPase Activities of Glycine max Seeds by PEG Treatment

The soybean （Glycine max） Heihe No. 23 is sensitive to imbibitional chilling injury. Polyethylene glycol （PEG） treatment can improve chilling tolerance of soybean seeds to a certain extent. The changes of hydrolytic ATPase in plasma membranes and H^＋-pumping responses in soybean seeds were investigated during PEG treatments. Effects of exogenous calcium and exogenous ABA on the hydrolytic ATPase were also examined in order to understand the mechanism of chilling resistance. Highly purified plasma membranes were isolated by 6.0% aqueous two-phase partitioning from soybean seeds, as judged by the sensitivity of hydrolytic ATPase to sodium vanadate. PEG treatment resulted in a slight increase of the hydrolytic ATPase activity in 12 h. Then the activity decreased gradually, but still higher than the control. The H^＋-pumping activity increased steadily during PEG treatment. Exogenous calcium had both activating and inhibiting effects on the hydrolytic ATPase, but the activity was inhibited in soybean seeds treated with exogenous ABA. Results suggested that PEG treatment, not the exogenous calcium and ABA, up-regulated H^＋-ATPase activities in soybean seeds.

Plasma Membrane Calcium ATPase Expression in Human Lens Epithelium Cell Lines

Purpose:To study the expression of four plasma membrane calcium ATPase (PMCA) isoforms in human lens epithelium cell lines (HLE-B3 cells) both on mRNA and protein levels.Methods:Both total mRNA and membrane protein samples were collected,after HLE-B3 cells were cultured to 90% confluency.Reverse Transcription Polymerase Chain Reaction (RT-PCR) were used to detect mRNAs of PMCA isoform 1,2,3,and 4 by using corresponding PMCA isoform 1,2,3,and 4 primers.Western Blot analysis was employed to detect PMCA isoform 1,2,3,and 4 protein using corresponding anti-PMCA1,2,3,and 4 antibodies.Results:A 420 bp fragment was amplified with PMCA1 primer.A 550 bp fragment was amplified with PMCA2 primer.A 840 bp fragment was amplified with PMCA4 primer.No fragment was amplified with PMCA3 primer.Western Blotting confirmed that the expected ～153 kDa,～125 kDa and ～147 kDa protein were recognized by anti PMCA1,2 and 4 antibodies respectively.No protein was recognized by PMCA3 antibody.Conclusion:This is the first study showing only PMCA1,2,and 4 gene are expressed in HLE-B3 cells on both mRNA and protein level.PMCA3 is not expressed in HLE-B3 cells.The PMCA isoforms expression pattern in HLE-B3 cell lines is different from that in the lens of other species.PMCA2 may play a more important role over other isoforms.

Effects of Calcium on ATPase Activity and Lipid omposition of Plasma Membranes from Wheat Roots Under Aluminum Stress

Effects of calcium on ATPase activities, lipid contents, and fatty acid compositions of plasma membrane from wheat roots were assayed under aluminum stress. The results showed that the increase of calcium concentration in the nutrient solution increased the activity of H + ATPase and the phospholipid content, decreased the activity of Ca 2+ ATPase and the galactolipid of plasma membrane. Owing to the decrease of linolenic acid content, the index of unsaturated fatty acid (IUFA) and index of double bond (DBI) decreased in Altas66. The IUFA and DBI of plasma membrane from Scout66 roots increased because its linolenic acid content increased obviously and its palmitic acid content decreased apparently.

Contribution of plasma membrane Ca^(2+) ATPase to cerebellar synapse function

The cerebellum expresses one of the highest levels of the plasma membrane Ca2+ATPase,isoform 2 in the mammalian brain.This highly efficient plasma membrane calcium transporter protein is enriched within the main output neurons of the cerebellar cortex;i.e. the Purkinje neurons(PNs) .Here we review recent evidence,including electrophysiological and calcium imaging approaches using the plasma membrane calcium ATPase 2(PMCA2) knockout mouse,to show that PMCA2 is critical for the physiological control of calcium at cerebellar synapses and cerebellar dependent behaviour.These studies have also revealed that deletionof PMCA2 throughout cerebellar development in the PMCA2 knockout mouse leads to permanent signalling and morphological alterations in the PN dendrites. Whilst these findings highlight the importance of PMCA2 during cerebellar synapse function and development,they also reveal some limitations in the use of the PMCA2 knockout mouse and the need for additional experimental approaches including cell-specific and reversible manipulation of PMCAs.

Role of platelet plasma membrane Ca^(2+)-ATPase in health and disease

Platelets have essential roles in both health and disease. Normal platelet function is required for hemostasis.Inhibition of platelet function in disease or by pharmacological treatment results in bleeding disorders.On the other hand,hyperactive platelets lead to heart attack and stroke.Calcium is a major second messenger in platelet activation,and elevated intracellular calcium leads to hyperactive platelets.Elevated platelet calcium has been documented in hypertension and diabetes;both conditions increase the likelihood of heart attack and stroke. Thus,proper regulation of calcium metabolism in the platelet is extremely important.Plasma membrane Ca2+-ATPase(PMCA)is a major player in platelet calcium metabolism since it provides the only significant route for calcium efflux.In keeping with the important role of calcium in platelet function,PMCA is a highly regulated transporter.In human platelets,PMCA is activated by Ca2+/calmodulin,by cAMP-dependent phosphorylation and by calpain-dependent removal of the inhibitory peptide.It is inhibited by tyrosine phosphorylation and calpain-dependent proteolysis.In addition,the cellular location of PMCA is regulated by a PDZ-domain-dependent interaction with the cytoskeleton during platelet activation.Rapid regulation by phosphorylation results in changes in the rate of platelet activation,whereas calpain-dependent proteolysis and interaction with the cytoskeleton appears to regulate later events such as clot retraction.In hypertension and diabetes,PMCA expression is upregulated while activity is decreased, presumably due to tyrosine phosphorylation.Clearly,a more complete understanding of PMCA function in human platelets could result in the identification of new ways to control platelet function in disease states.

Effects of Calcium on the GABA_A-Coupled CI^-/HCO₃^--ATPase from Plasma Membrane of Rat Brain

The work is a study of the influence of Ca2+ (0.01 - 1 mM) on neuronal CI-, HCO3-, -ATPase complex: an enzyme that is a CI--pump which is functionally and structurally coupled to GABAA-receptors. It is found that influence of Ca2+ on the multifunctional complex starts at concentration of 50·M and at concentration of 0.1 mM, it reduces the “basal” one and increases the CI-, HCO3-, -stimulated Mg2+-ATPase activities. GABA (0.1 - 100μM) activates the “basal” Mg2+-ATPase activity in the ab-sence of calcium. The effect of GABA on the enzyme in the presence of 0.01 ·M Ca2+ does not change. At the same time, 1 mM Ca2+eliminates the GABA effect on the “basal” Mg2+-ATPase activity. Competitive blocker of GABAA-receptors bicuculline (5 - 20 μM) in the absence of Ca2+ ions elimi-nates the stimulation of the “basal” Mg2+-ATPase by anions. When 0.25 mM Ca2+ is added to the in-cubation medium the inhibitory bicuculline effect on the enzyme does not appear. We found that 0.1 mM o-vanadate (protein tyrosine phosphatase blocker) reduces the GABA-activated ATPase activity. At the same time, 0.1 mM genistein (a protein tyrosine kinase blocker) has no effect on enzyme activity. In the presence of Ca2+ (0.25 mM), the effect of o-vanadate on the “basal” and CI-, HCO3-, -ATPase activities does not appear. It is shown for the first time that high concentrations of Ca2+prevent the action of GABAA-ergic ligands on the study ATPase. It is assumed that there is the involvement of protein kinases and protein phosphatases in the modulation of the enzyme activity by calcium. The observed effect of calcium on the ATPase may play an important role in the study of the mechanisms of epileptogenesis and seizure activity.

质膜H^(+)-ATPase基因对铝胁迫下水稻硝态氮吸收的 调控作用

为探讨细胞质膜ATP酶(PM H^(+)-ATPase)基因对铝胁迫下水稻(Oryza sativa L.)吸收硝态氮(NO_(3)^(-)-N)的调控,本试验以2个水稻品种峰1A和峰1A优5为研究对象,以无铝处理幼苗为对照,分析铝胁迫下水稻根尖PM H^(+)-ATPase活性、H^(+)-泵活性、H^(+)通量、PM H^(+)-ATPase基因家族(OsA1~OsA10)表达水平、PM H^(+)-ATPase和14-3-3蛋白的互作水平以及NO_(3)^(-)-N吸收量。结果表明,与对照相比,铝胁迫下2个水稻品种根尖PM H^(+)-ATPase活性、H^(+)-泵活性和根尖H^(+)通量下降,PM H^(+)-ATPase和14-3-3蛋白的互作水平下降。铝胁迫抑制了OsA1、OsA5、OsA7和OsA8基因的表达,其中OsA7的表达水平显著下调,铝胁迫下峰1A和峰1A优5的OsA7表达量仅为对照组的21%和39%。NO_(3)^(-)-N吸收量较对照下降,分别为对照的81%和85%。综上,PM H^(+)-ATPase基因的表达水平影响水稻对NO_(3)^(-)-N的吸收能力,OsA1、OsA5、OsA7和OsA8在铝胁迫下水稻吸收NO_(3)^(-)-N过程中起关键的调控作用。本研究结果可为增强酸铝条件下水稻吸收NO_(3)^(-)-N的能力,促进水稻生长及增产提供理论依据。

Ca^(2+)-ATPase参与植物耐盐性调控的研究进展

盐胁迫下细胞质Ca^(2+)浓度升高,细胞会激活Ca^(2+)调节的靶酶或者与Ca^(2+)高度亲和的受体蛋白,其中,与Ca^(2+)高度亲和的受体蛋白中,植物钙泵(Ca^(2+)-ATPase)是P型ATP酶,包含内质网Ca^(2+)-ATPases与质膜Ca^(2+)-ATPas‐es,通过主动运输将Ca^(2+)从细胞质转移到质外体或细胞器。大量研究表明,植物的耐盐性在很大程度上与其维持钙泵即Ca^(2+)-ATPase活性的能力有关。多种植物Ca^(2+)-ATPase对盐胁迫表现出敏感性,并受到外源Ca^(2+)的保护,表明外源钙处理与Ca^(2+)-ATPase活性可能在盐胁迫下的细胞内钙稳态和信号转导中起重要作用。该研究概述了植物Ca^(2+)-ATPase类型、结构与性质,亚细胞定位Ca^(2+)-ATPase及外源钙与亚细胞定位Ca^(2+)-ATPase参与植物耐盐调控研究进展,重点对质膜、液泡膜、核膜、内质网及高尔基体Ca^(2+)-ATPases参与植物耐盐调控的研究进展进行了综述,并提出展望。该研究为了解植物耐盐性生理及分子机制提供帮助,同时为作物耐盐栽培提供新思路。

Plasma membrane calcium pumps and their emerging roles in cancer

Alterations in calcium signaling and/or the expression of calcium pumps and channels are an increasingly recognized property of some cancer cells.Alterations in the expression of plasma membrane calcium ATPase(PMCA) isoforms have been reported in a variety of cancer types,including those of breast and colon,with some studies of cancer cell line differentiation identifying specific PMCA isoforms,which may be altered in some cancers.Some studies have also begun to assess levels of PMCA isoforms in clinical tumor samples and to address mechanisms of altered PMCA expression in cancers.Both increases and decreases in PMCA expression have been reported in different cancer types and in many cases these alterations are isoform specific.In this review,we provide an overview of studies investigating the expression of PMCA in cancer and discuss how both the overexpression and reduced expression of a PMCA isoform in a cancer cell could bestow a growth advantage,through augmenting responses to proliferative stimuli or reducing sensitivity to apoptosis.

Plasma membrane calcium pump regulation by metabolic stress

The plasma membrane Ca2+-ATPase(PMCA)is an ATPdriven pump that is critical for the maintenance of low resting[Ca2+]i in all eukaryotic cells.Metabolic stress, either due to inhibition of mitochondrial or glycolytic metabolism,has the capacity to cause ATP depletion and thus inhibit PMCA activity.This has potentially fatal consequences,particularly for non-excitable cells in which the PMCA is the major Ca2+efflux pathway.This is because inhibition of the PMCA inevitably leads to cytosolic Ca2+ overload and the consequent cell death.However,the relationship between metabolic stress,ATP depletion and inhibition of the PMCA is not as simple as one would have originally predicted.There is increasing evidence that metabolic stress can lead to the inhibition of PMCA activity independent of ATP or prior to substantial ATP depletion.In particular,there is evidence that the PMCA has its own glycolytic ATP supply that can fuel the PMCA in the face of impaired mitochondrial function.Moreover, membrane phospholipids,mitochondrial membrane potential,caspase/calpain cleavage and oxidative stress have all been implicated in metabolic stress-induced inhibition of the PMCA.The major focus of this review is to challenge the conventional view of ATP-dependent regulation of the PMCA and bring together some of the alternative or additional mechanisms by which metabolic stress impairs PMCA activity resulting in cytosolic Ca2+ overload and cytotoxicity.

质膜ATP酶作为新型杀真菌剂靶标的发现与应用

质膜H+-三磷酸腺苷酶(plasma membrane H+-ATPase,PMA),简称质膜ATP酶,属于质子泵家族蛋白,广泛存在于植物和真菌的质膜上;它们的主要作用是维持细胞营养摄取所需的跨膜电化学质子梯度和调控pH值。质膜ATP酶是真菌生命活动所必须的,该酶缺失后,突变体的生长出现明显缺陷甚至无法生长,这使其具有作为杀真菌剂靶标的潜力;另外,由于真菌和植物的质膜ATP酶同源性较低,故以质膜ATP酶为靶标开发的杀真菌剂具有生物安全性。最近明确的酿酒酵母Saccharomyces cerevisiae和粗糙脉孢霉Neurospora crassa质膜ATP酶的冷冻电镜结构揭示了其六聚体的状态,阐明了质膜ATP酶的作用机制,为基于结构的药物设计提供了理论基础。本文主要对真菌中质膜ATP酶的结构和功能进行系统阐述,并对质膜ATP酶作为新型杀真菌剂靶标的研究现状进行综述,旨在为新型杀真菌剂的发现和应用提供理论依据。

钙离子转运ATP酶B2杂合突变导致小鼠渐进性前庭功能障碍

目的·研究不同月龄钙离子转运ATP酶B2(ATPase plasma membrane Ca^(2+)transporting 2,ATP2B2)Oblivion杂合突变小鼠前庭毛细胞结构和前庭功能的变化。方法·选取2月龄及8月龄Atp2b2 Oblivion杂合突变雄性小鼠各10只,以同龄C57BL/6J野生型雄性小鼠作为对照。通过免疫荧光实验观察不同月龄2组小鼠前庭毛细胞ATP2B2表达情况,并对微纹区及纹外区毛细胞数量进行统计;通过扫描电子显微镜(电镜)观察小鼠前庭毛细胞纤毛形态;通过透射电镜观察小鼠前庭毛细胞带状突触和线粒体;采用前庭诱发电位(vestibular evoked potential,VsEP)、前庭肌源性诱发电位(vestibular evoked myogenic potential,VEMP),及转棒、平衡木实验检测小鼠的前庭功能。结果·2组小鼠ATP2B2均主要表达于前庭毛细胞纤毛,2月龄及8月龄Atp2b2 Oblivion杂合突变小鼠微纹区及纹外区毛细胞数量与野生型小鼠均无明显差异。扫描电镜下,2月龄及8月龄杂合突变小鼠椭圆囊毛细胞纤毛无明显结构异常。透射电镜下,2月龄杂合突变小鼠前庭毛细胞表皮板与神经连接部位附近的线粒体结构无异常,突触结构无异常;8月龄杂合突变小鼠前庭毛细胞表皮板附近线粒体出现空泡样变性,神经连接部位附近的线粒体及突触结构无异常。2月龄及8月龄杂合突变小鼠VsEP及VEMP阈值均较野生型小鼠显著上升,VsEP波形分析显示杂合突变小鼠P1潜伏期延长,P1N1波幅降低(均P<0.05)。2月龄杂合突变小鼠转棒、平衡木实验结果未见明显改变,但8月龄杂合突变小鼠完成转棒、平衡木能力较野生型小鼠显著下降(均P<0.05)。结论·Atp2b2 Oblivion杂合突变小鼠2月龄时前庭电生理功能下降,8月龄时出现前庭相关行为学异常,Atp2b2 Oblivion杂合突变小鼠呈渐进性前庭功能障碍。

盐胁迫对小麦根质膜ATPase活性的影响

以小麦为实验材料,研究了盐胁迫对根质膜H^+-ATPase、Ca^(2+)-ATPase活性及H^+-ATPase蛋白表达的影响。结果显示:50、100、150mmol/L的NaCl处理72h后,小麦根质膜H^+-ATPase、Ca^(2+)-ATPase活性均降低。100mol/L NaCl对质膜ATPases活性的抑制程度随处理时间的延长而增强,在处理24h后,H^+-ATPase和Ca^(2+)-ATPase的活性分别降为对照的72％和75％,而处理72h后,酶活性分别减小到对照的50％和48％。50、100、150mmol/L的NaCl直接作用于提取的质膜微囊,H^+-ATPase的活性分别降低约5％、8％和16％。Western blotting分析结果显示100mmol/L NaCl处理72h后,质膜H^+-ATPase的含量与对照比有所减少。本研究表明:盐胁迫抑制小麦根质膜H^+-ATPase、Ca^(2+)-ATPase的活性,酶含量的减少可能是盐胁迫导致质膜H^+-ATPase活性降低的原因。

水稻根系细胞膜H^+-ATPase对铵硝营养的响应差异

用两相法分离了铵态氮(NH4+-N)和硝态氮(NO3--N)营养下水稻苗期根系的细胞膜,并测定了细胞膜上H+-ATPase的水解活性,以期阐明水稻根系细胞质膜上H+-ATPase对不同氮素形态的响应差异。两相法分离的细胞膜纯度达到95%以上。在离体条件下,NH4+-N营养的水稻根系细胞膜H+-ATPase的水解活性和H+-ATPase的Km和Vmax均显著高于NO3--N营养。NH4+-N营养的水稻根系细胞膜H+-ATPase最适pH值为6.0,而NO3--N营养的在pH6.2左右。Westernblot结果表明,NH4+-N营养的水稻根系细胞膜H+-ATPase浓度显著高于NO3--N营养的H+-ATPase。说明NH4+-N营养的水稻根系细胞膜H+-ATPase活性高是因为单位细胞膜上的H+-ATPase分子数量大于NO3--N营养,并且在NH4+-N营养的水稻根系细胞膜上可能存在着与NO3--N营养不同的H+-ATPase的同工酶。因此,NH4+-N营养的水稻根系细胞膜H+-ATPase活性高很可能是水稻根系对铵态氮营养的一种适应机制。

盐胁迫及La^(3+)对不同耐盐性水稻根中抗氧化酶及质膜H^+-ATPase的影响

用盐敏感的武运粳8号和强耐盐的韭菜青两个粳稻品种,比较了盐胁迫条件下根中抗氧化酶类和质膜H+-ATPase活性的变化以及La3+对其变化的影响。结果表明,两个品种根中SOD和APX活性无显著区别,但耐盐品种的CAT和POD活性强于盐敏感品种。盐胁迫不同程度地提高了两者抗氧化酶活性。La3+对其影响最显著的差异出现在高盐条件下(200~300mmolL-1NaCl),对耐盐品种添加La3+可以提高上述4种酶的活力,而对盐敏感品种,La3+的作用不明显。对盐敏感品种,盐胁迫导致其质膜H+-ATPase活性持续下降,添加La3+明显提高其H+-ATPase活性,而对耐盐品种,盐胁迫导致其质膜H+-ATPase活性呈现先降后升的趋势,La3+对其活性影响不大。进一步分析表明,上述H+-ATPase活性变化及La3+对其影响均发生在转录水平上。据此推测,以上2个品种可能具有完全不同的盐胁迫响应机制。