柴胡皂甙和甘草甜素抑制Na+,K+-ATP酶活性的构效关系

研究在离体条件下各种单体柴胡皂甙和甘草甜素抑制Na⁺,K⁺-ATP酶活性的构效关系。实验结果表明,各种柴胡皂甙抑制Na⁺,K⁺-ATP酶活性的作用强度依次为:b₁>d>b₂>b₄>a>b₃>e>c。柴胡皂甙化学结构中的C₂₃-OH,C₁₆-OH及C₁₁和C₁₃的共轭双烯可能对其抑制活性起重要作用。甘草甜素(GL),甘草次酸(GA)和生胃酮(18-β-甘草次酸半琥珀酸双钠盐,CX)抑制Na⁺,K⁺-ATP酶活性的作用强度依次为GA≥CX>GL。研究还证明,柴胡皂甙d对Na⁺,K⁺-ATP酶的抑制为非竟争性抑制。     

四肽FMRFa对大鼠心室肌Na+/Ca2+交换的抑制

目的　研究四肽FMRFa对大鼠单个心室肌细胞Na⁺/Ca²⁺交换的作用。方法　用膜片钳全细胞记录法测定成年大鼠心室肌细胞Na⁺/Ca²⁺交换电流(I_Na⁺/Ca²⁺)和其他离子通道电流。结果　FMRFa对大鼠心室肌细胞I_Na⁺/Ca²⁺呈浓度依赖性抑制,100μmol·L^-1浓度时抑制内向和外向I_Na⁺/Ca²⁺密度分别达60.1%和56.5%,对内向电流及外向电流的IC₅₀分别为20μmol·L^-1和34μmol·L^-1。FMRFa5μmol·L^-1抑制I_Na⁺/Ca²⁺内向和外向电流密度分别为38.7%和34.9%,但FMRFa5μmol·L^-1及20μmol·L^-1对L型钙电流、钠电流、瞬时外向电流和内向整流钾电流均无显著抑制作用。结论　FMRFa对大鼠心室肌细胞是一个特异性Na⁺/Ca²⁺交换抑制剂。     

芪参胶囊对大鼠局灶性脑缺血再灌注损伤的保护作用

目的研究芪参胶囊对大鼠局灶性脑缺血再灌注损伤的保护作用。方法用线栓法建立大鼠局灶性脑缺血模型,大鼠于缺血1h再灌注2h断头取脑,检测大脑组织Ca²⁺]-ATPase,Na⁺],K⁺]-ATPase,NOS活性和NO,水的含量及大脑皮层神经元内游离钙离子浓度,行为学评价及梗死面积,常规石蜡切片,HE染色,作病理学检查。结果芪参胶囊显著降低缺血再灌注后大脑皮层神经元内游离钙离子浓度及大脑组织NOS活性,NO的含量和水肿程度及梗死面积;显著增强Ca²⁺]-ATPase,Na⁺],K⁺]-ATPase的活性;病理学检查显示芪参胶囊能明显减轻脑水肿及神经元坏死程度。结论芪参胶囊对大鼠局灶性脑缺血再灌注损伤有明显保护作用。     

中药大黄的生化学研究ⅩⅫ蒽醌衍生物对兔肾髓质Na+-K+-ATP酶活性的抑制和利尿作用

家兔实验表明:大黄素、大黄酸以30 mg/kg的剂量灌胃给药,2～4h后尿量、排Na⁺和K⁺量达最高峰,比对照组明显增多。而芦荟大黄素和大黄酚的作用较弱。大黄素、大黄酸和芦荟大黄素对免肾髓质Na⁺-K⁺-ATP酶活性有较强的竞争性抑制作用。     

KB-R7943对豚鼠心室肌细胞Na+-Ca2+交换电流的作用

目的　观察KB-R7943对豚鼠心室肌细胞Na⁺-Ca²⁺交换电流(I_Na-Ca)的内向电流成分和外向电流成分的影响。方法　采用缺血再灌时胞内Na⁺超载的细胞模型,在同时记录内向、外向电流的双向离子条件下,用膜片钳全细胞技术,记录I_Na-Ca的电流-电压关系曲线。结果　10^-6和10^-5mol·L^-1KB-R7943,在+50mV时,对I_Na-Ca的抑制率分别是29.4%和61.7%;在-80mV时抑制率分别是22.1%和56.9%。结论　KB-R7943对豚鼠心室肌细胞I_Na-Ca有抑制作用,但对外向成分和内向成分的抑制不具选择性。     

前胡香豆素对肾型高血压大鼠左室肥厚及心肌胞内钙、Na+,K+-ATP酶和Ca2+,Mg2+-ATP酶活性的影响

目的研究前胡香豆素组分对肾型高血压左室肥厚的预防和逆转作用及机制。方法用两肾一夹肾型高血压左室肥厚大鼠(RHR)模型,测定前胡香豆素组分对其血压、左室湿重、心肌细胞面积、胞内静息钙及胞膜和线粒体ATP酶活性的影响。结果前胡香豆素组分(30 mg·kg^-1·d^-1,ig)预防组及逆转组大鼠血压、左室湿重/体重均较肥厚组明显降低;左室心肌细胞面积、胞内静息钙均较肥厚组降低;对KCl致钙浓度升高亦明显低于肥厚组;两组均可增加心肌细胞膜及线粒体Na⁺,K⁺-ATP酶和Ca²⁺,Mg²⁺-ATP酶活性。结论前胡香豆素组分可预防及逆转RHR左室肥厚,减少心肌细胞内钙含量,增加ATP酶活性。     

儿童过敏性鼻炎治疗前后外周血CD4+CD25+CD127lo/-Treg细胞与炎症因子变化分析

目的 探讨儿童过敏性鼻炎（AR）治疗前后外周血CD4⁺CD25⁺CD127^lo/-Treg及白细胞介素2（IL-2）、肿瘤坏死因子α（TNF-α）、人转化生长因子β1（TGF-β1）的水平变化及临床意义。方法 将厦门长庚医院收治的108例AR患儿作为AR组,根据疾病严重程度分为轻度、中重度组,另采用单纯随机抽样法选取年龄、性别匹配的80例健康儿童作为对照组,检测两组对象入院时CD4⁺CD25⁺CD127^lo/-Treg、IL-2、TNF-α、TGF-β1水平;AR患者均给予对症治疗,检测治疗前、治疗1个月、治疗6个月CD4⁺CD25⁺CD127^lo/-Treg、IL-2、TNF-α、TGF-β1水平,采用Pearson相关分析疾病严重程度与外周血CD4⁺CD25⁺CD127^lo/-Treg的相关性及两者与IL-2、TNF-α、TGF-β1相关性。结果 AR患者CD4⁺CD25⁺CD127^lo/-Treg、IL-2、TGF-β1水平分别为（6.264±0.135）%、（50.16±11.67）ng/L、（14.21±5.34）ng/L,均低于对照组;TNF-α为（1.82±0.62）ng/L,高于对照组的（0.34±0.19）ng/L,差异均有统计学意义（P<0.05）。轻度AR患者CD4⁺CD25⁺CD127^lo/-Treg、IL-2、TGF-β1水平分别为（6.305±0.137）%、（59.34±13.05）ng/L、（16.97±4.69）ng/L,均高于中重度AR组患者,TNF-α水平为（1.64±0.57）ng/L,低于中重度AR组患者的（1.93±0.65）ng/L,差异均有统计学意义（P<0.05）。AR组治疗后第1、6个月CD4⁺CD25⁺CD127^lo/-Treg、IL-2、TGF-β1水平高于治疗前,TNF-α水平低于治疗前,差异均有统计学意义（P<0.05）。Pearson相关分析显示：外周血CD4⁺CD25⁺CD127^lo/-Treg、TNF-α与疾病严重程度呈正相关关系（r=0.681、0.581,P<0.05）,IL-2、TGF-β1与疾病严重程度呈负相关关系（r=-0.613、-0.579,P<0.05）;外周血CD4⁺CD25⁺CD127^lo/-Treg与IL-2、TGF-β1呈负相关性（r=-0.675、-0.691,P<0.05）,与TNF-α呈正相关关系（r=0.618,P<0.05）。结论 AR患者存在CD4⁺CD25⁺CD127^lo/-Treg及IL-2、TGF-β1下降,TNF-α上升,且与病情程度有关,治疗后均明显改善。     

CD4+CD25+调节性T淋巴细胞在儿童传染性单核细胞增多症的变化及作用

目的 观察儿童传染性单核细胞增多症（IM）治疗前后外周血T淋巴细胞亚群和CD4⁺CD25⁺调节性T淋巴细胞（Treg细胞）比例变化,分析Treg对IM的影响。方法 选取2017年1月至2018年5月安徽医科大学第二附属医院儿科收治的IM患儿60例作为观察组,以同期于本院儿童保健门诊行体检的40例健康儿童作为对照组,采用流式细胞术检测观察组治疗前、后及对照组的外周血T细胞亚群（CD3⁺T细胞、CD3⁺CD4⁺T细胞、CD3⁺CD8⁺T细胞比例,CD4/CD8比值）、CD4⁺CD25⁺调节性T淋巴细胞比例,对比分析两组患者机体细胞免疫功能的变化。结果 观察组治疗前CD3⁺T细胞比例、CD3⁺CD8⁺T细胞比例显著高于对照组;CD3⁺CD4⁺T细胞比例、CD4/CD8比值低于对照组,差异均有统计学意义（P <0.05）。观察组治疗后CD3⁺T细胞比例、CD3⁺CD8⁺T细胞比例均低于观察组治疗前;CD3⁺CD4⁺T细胞比例、CD4/CD8比值高于治疗前,差异均有统计学意义（P <0.05）。观察组治疗前外周血Treg细胞比例低于正常对照组,差异有统计学意义（P <0.05）;而观察组治疗后外周血Treg细胞比例高于治疗前,差异有统计学意义（P <0.05）。结论 IM患儿存在T细胞亚群比例的变化,Treg细胞水平的降低,可能参与IM患儿疾病的发生发展过程。     

人参二醇皂甙和三醇皂甙对兔纹状体ATP酶的影响

本文报道用体外给药法,观察了PDS和PTS对纹状体ATP酶(Na⁺、K⁺-ATP酶,Ca²⁺-ATP酶及M²⁺-ATP酶)的影响。结果发现PDS和PTS对Na⁺,K⁺-ATP酶都有明显的抑制作用,且随PDS和PTS浓度的高低,其抑制作用增强或减弱;对Ca²⁺-ATP酶,PDS在10^-5g/ml时有激活作用,当浓度增高到10^-3g/mL时则转为抑制,而PTS仅为抑制效应;对于Mg²⁺-ATP酶能被PDS所兴奋,而被PTS所抑制。此结果表明PDS和PTS对中枢神经系统的作用,可能与其影响脑内ATP酶有密切的内在联系。     

阿托伐他汀的肝毒性机制研究

目的 研究阿托伐他汀肝毒性损伤作用及机制。方法 将24只Wistar han雄鼠分为对照组和阿托伐他汀低（68.5mg/kg）、高剂量组（205.5 mg/kg）,按照10 mL/kg的药液体积给药,溶媒对照组ig等体积5% CMC-Na,连续ig 28 d。检测血清中天门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）、碱性磷酸酶（ALP）、尿素氮（BUN）和血肌酐（CRE）的含量,HE染色观察肝组织病理。在体外,HepG2细胞经传代培养后,给予阿托伐他汀干预24 h,检测细胞存活率,丙二醛（MDA）水平、Na⁺-K⁺-ATP酶和Ca²⁺-Mg²⁺-ATP酶活性及线粒体膜电位。结果 与对照组比较,阿托伐他汀高剂量组大鼠肝细胞弥漫性肿胀,核分裂多见,部分肝细胞极性消失,排列紊乱（P<0.05）。与对照组比较,阿托伐他汀高剂量组给药后血清中ALT和AST显著升高（P<0.05、0.01）。在体外,与对照组比较,阿托伐他汀125、250、500 μmol/L能明显抑制细胞存活率（P<0.05、0.001）。与对照组比较,阿托伐他汀500 μmol/L HepG2细胞MDA含量明显升高（P<0.01）。与对照组比较,阿托伐他汀125 μmol/L能使Na⁺-K⁺-ATP酶活性增强,500 μmol/L使Na⁺-K⁺-ATP酶活性降低（P<0.001）。与对照组比较,阿托伐他汀125、250、500 μmol/L均能使能使Ca²⁺-Mg²⁺-ATP酶活性降低（P<0.01,0.001）。与对照组比较,阿托伐他汀125、250、500 μmol/L均能降低线粒体膜电位（P<0.001）。结论 阿托伐他汀高剂量可导致肝组织损伤,其毒性作用通过破坏细胞的线粒体膜电位,抑制Na⁺-K⁺-ATP酶、Ca²⁺-Mg²⁺-ATP酶活性,细胞膜脂质过氧化,从而破坏细胞内微环境的平衡,导致细胞凋亡和坏死。     

Effects of monovalent cations on (Na+ + K+)-ATPase in rat brain slices.

The influence of monovalent cations on membrane (Na + K+)-ATPase was estimated in vitro in intact cells from the oxygen consumption of rat brain cortical slices. High concentrations of K+, Rb+ or Cs+ stimulated the respiration in the presence of Na+. This stimulation was antagonized by ouabain in a concentration- and time-dependent manner. Additionally, only combinations of monovalent cations, that stimulate (Na+ + K+)-ATPase, increased oxygen consumption, indicating that the stimulated portion of respiration is realted to the (Na+ + K+)-ATPase activity. Low concentrations of Rb+ and Cs+, however, failed to affect oxygen consumption. Li+ slightly and transiently stimulated oxygen uptake at low concentrations and inhibited it at higher concentrations. Low concentrations of Tl+ also stimulated respiration in a K+-free medium. However, the inhibitory effects of Tl+ were predominant at higher concentrations or in the presence of K+. Thus, monovalent cations can alter (Na+ + K+)-ATPase activity. While Rb+ and Li+ produce opposite effects on this enzyme system under certain conditions, these actions do not seem to be related to the antidepressant action of Rb+ and the antimanic action of Li+.     

匹诺塞林对急性局灶性脑缺血大鼠脑线粒体功能的影响

目的考察匹诺塞林对大鼠急性局灶性脑缺血组织能量代谢及线粒体功能的影响。方法制备永久性大鼠大脑中动脉栓塞(pMCAO)模型,大鼠随机分为假手术组、模型组、匹诺塞林给药组(1、3、10 mg.kg-1)、尼莫地平给药组(3mg.kg-1)。给药组于手术后10 min、12 h分别给予静脉注射,假手术组与模型组给予生理盐水。于手术24 h应用生化方法检测脑组织中LDH的活性,HPLC法检测大鼠脑组织ATP、ADP、AMP、磷酸肌酸含量。通过检测线粒体超氧化物歧化酶(Mn-SOD)、线粒体Ca2+-ATP酶活性,超氧阴离子含量、线粒体膜肿胀度、线粒体钙离子含量综合评价线粒体功能。结果匹诺塞林(3、10 mg.kg-1)给药组大鼠缺血脑组织中乳酸脱氢酶活性降低,能量指数比模型组分别提高了34.6%和45.8%(P<0.05);匹诺塞林(10 mg.kg-1)组线粒体SOD活性提高了24.4%、Na+,K+-ATP酶、Ca2+-ATP酶活性分别升高了24.9%及34.0%,线粒体钙离子浓度降低了22.0%,与模型组相比差异均具有显著性(P<0.05)。匹诺塞林(3、10 mg.kg-1)组线粒体超氧阴离子水平分别降低了20.2%及30.6%、线粒体肿胀程度分别降低了26.1%及46.0%,与模型组相比差异均具有显著性(P<0.05)。结论匹诺塞林可减轻大鼠脑缺血后能量损伤,提高脑组织抗缺血缺氧能力,其对线粒体功能的保护作用可能是改善缺血脑组织能量代谢的重要机制。     

Involvement of cAMP/cAMP-dependent protein kinase signaling pathway in regulation of Na+,K+-ATPase upon activation of opioid receptors by morphine

The depolarization of neurons induced by impairment of Na+,K+-ATPase activity after long-term opiate treatment has been shown to involve the development of opioid dependence. However, the mechanisms underlying changes in Na+,K+-ATPase activity after opioid treatment are unclear. The best-established molecular adaptation to long-term opioid exposure is up-regulation of the cAMP/cAMP-dependent protein kinase (PKA) signaling pathway; this study, therefore, was undertaken to investigate the role of up-regulation of cAMP/PKA signaling pathway in alteration of the mouse hippocampal Na+,K+-ATPase activity. The results demonstrated that short-term morphine treatment dose dependently stimulated Na+,K+-ATPase activity. This action could be significantly suppressed by adenylyl cyclase activator 7beta-acetoxy-8,13-epoxy-1alpha,6beta,9alpha-trihydroxylabd-14-en-11-one (forskolin), or the cAMP analog dibutyryl-cAMP. Contrary to short-term morphine treatment, long-term treatment significantly inhibited Na+,K+-ATPase activity. Moreover, an additional decrease in Na+,K+-ATPase activity was observed by naloxone precipitation. The effects of both short- and long-term morphine treatment on Na+,K+-ATPase activity were naltrexone-reversible. The regulation of Na+,K+-ATPase activity by morphine was inversely correlated with intracellular cAMP accumulation. N-[2-(4-Bromocinnamylamino)ethyl]-5-isoquinoline (H89), a specific PKA inhibitor, mimicked the stimulatory effect of short-term morphine but antagonized the inhibitory effect of long-term morphine treatment on Na+,K+-ATPase activity. However, okadaic acid, a protein phosphatase inhibitor, suppressed short-term morphine stimulation but potentiated long-term morphine inhibition of Na+,K+-ATPase activity. The regulation of Na+,K+-ATPase activity by morphine treatment seemed to associate with the alteration in phosphorylation level but not to be relevant to the change in abundance of Na+,K+-ATPase. These findings strongly demonstrate that cAMP/PKA signaling pathway involves regulation of Na+,K+-ATPase activity after activation of opioid receptors.     

Effect of isoflurane on proliferation and Na+,K+-ATPase activity of alveolar type II cells injured by hydrogen peroxide

The influence of isoflurane (Iso) on proliferation and Na+,K+-ATPase activity of alveolar type II cells (ATII cells) injured by hydrogen peroxide (H2O2) was investigated. ATII cells isolated and purified from adult Sprague-Dawley rats were randomly divided into six groups: control group, 0.28 mM Iso group, 2.8 mM Iso group, 75 microM H2O2 group, 75 microM H2O2 + 0.28 mM Iso group, and 75 microM H2O2 + 2.8 mM Iso group. After primary culture for 32 hours, the proliferation of ATII cells was detected by MTT assay, and after culture for 24 hours the activity of Na+,K+-ATPase and lactate dehydrogenase (LDH) in the cells, and malonaldehyde (MDA) content of the culture medium, were measured by colorimetry. It was found that 0.28 mM and 2.8 mM Iso had no effect on the proliferation of ATII cells (p > 0.05), but 75 microM H2O2 inhibited their proliferation (p < 0.05) compared with untreated controls; 0.28 mM and 2.8 mM Iso significantly decreased Na+,K+-ATPase activity of ATII cells compared with untreated control cells (p < 0.05), and 75 microM H2O2 markedly decreased Na+,K+-ATPase activity of ATII cells (p < 0.01) with untreated control cells. 0.28 mM and 2.8 mM Iso aggravated the decrease of Na+,K+-ATPase activity induced by H2O2. Iso had no effect on LDH activity and MDA content of the culture medium of normal ATII cells, but significantly increased LDH activity and MDA content of the culture medium of ATII cells injured by H2O2. These findings suggest that Iso itself may decrease the activity of Na+,K+-ATPase of ATII cells in vitro and further damage the cells' function under peroxidation conditions, but has no effect on the proliferation of ATII cells.     

蜂毒肽对豚鼠心肌线粒体Na~ 、K~ -ATP酶的影响(英文)

目的:研究蜂毒肽对豚鼠心肌线粒体Na~ ,K~ -ATP酶活性的影响。方法:应用光电比色法测定Na~ ,K~ -ATP酶活性。以Line-weaver-burk双倒数作图法分析酶动力学参数。结果:蜂毒肽抑制心肌Na~ ,K~ -ATP酶表现为浓度和时间依赖性,IC_(50)为2.60μmol/L。酶动力学研究表明,蜂毒肽对Na~ ,K~ -ATP酶有抑制作用,对K~ 表现为竞争性结合,对Na~ 及ATP表现为非竞争性结合。结论:蜂毒肽对心肌Na~ ,K~ -ATP酶有抑制作用,其抑制机制主要是与K~ 竞争结合酶外侧的K~ 结合位点。     

Inhibition of dog kidney Na+, K+-ATPase activity by procaine, tetracaine and dibucaine

The potency of local anesthetics as inhibitors of Na+, K+-ATPase and K+- NPPase activities correlated with lipid solubility. The order of potencies was: dibucaine greater than tetracaine much greater than procaine. Na+-ATPase activity was remarkably more sensitive to inhibition by tetracaine and procaine, and inhibitory potency did not correlate with lipid solubility. The order of potencies for inhibition of Na+-ATPase activity was: tetracaine greater than dibucaine greater than procaine. We examined interactions between the local anesthetics and monovalent cations in an attempt to explain this observation. Inhibition of Na+-K+-ATPase by tetracaine and dibucaine was competitive with respect to Na+, and inhibition of Na+-ATPase activity by all three agents was competitive with respect to Na+. Inhibition of Na+, K+-ATPase activity by procaine and tetracaine was competitive with respect to K+, and inhibition of K+- NPPase activity by all three agents was competitive with respect to K+. Dibucaine, the most lipid soluble agent, was equipotent as an inhibitor of all three activities and was generally less effective as a competitor with respect to activation by monovalent cations. These results suggest that dibucaine may interact nonspecifically with membrane lipids to inhibit enzyme activity whereas less lipid soluble agents, such as tetracaine and procaine, may interact more selectively with cation binding sites. It appears that the presence of K+ in the assay medium specifically decreases the inhibitory potency of tetracaine and procaine. Direct competition between these agents and K+ may prevent inhibition or, alternately, the presence of K+ may convert the enzyme to a conformation less susceptible to inhibition by agents of low to intermediate lipid solubility.     

Effects of oxidative stress on the erythrocyte Na+,K+ ATPase activity in female hyperthyroid patients.

This study was planned to determine the effects of free-radical-induced damage on the Na+,K+-ATPase activity of erythrocytes during hyperthyroidism and 4 wk after propylthiouracil (PTU) therapy (400 mg/d). The levels of plasma thiobarbituric acid-reactive substances (TBARS) as a marker of lipid peroxidation, erythrocyte glutathione (GSH) concentration as an antioxidant, blood ATP concentration, and erythrocyte membrane Na+,K+-ATPase activity were determined in female hyperthyroid patients (n = 22, mean age 40.5 +/- 6.5 yr). Before the PTU therapy, plasma TBARS concentration was significantly higher and the levels of blood ATP and erythrocyte GSH and the activity of membrane Na+,K-+-ATPase were significantly lower in the hyperthyroid patients (n = 15 women, mean age 40.8 +/- 7.3 yr). Four weeks after PTU therapy, plasma TBARS concentration was decreased, and levels of erythrocyte GSH and blood ATP and of Na+,K+-ATPase activity of erythrocytes were elevated in the treated patients. There was a significant positive correlation between blood ATP concentration and Na+,K+-ATPase activity, and a negative correlation between plasma TBARS concentration and Na+,K+-ATPase activity before PTU. Our results might help to clarify the effects of the oxidative mechanisms on the erythrocyte membrane Na+,K+-ATPase activity in hyperthyroid patients.     

Nitric oxide modulates Na+, K+-ATPase activity through cyclic GMP pathway in proximal rat trachea

The present work demonstrated that nitric oxide (NO) modulates Na+, K+-ATPase activity in the proximal rat trachea. Sodium nitroprusside induced concentration-dependent (10-100 microM) stimulation in proximal trachea Na+, K+-ATPase activity. The effect was specific for Na+, K+-ATPase since Mg-ATPase activity was unaffected. This NO-donor changed neither Na+, K+-ATPase nor Mg-ATPase activity in the distal segment. The modulatory action on Na+, K+-ATPase induced by sodium nitroprusside was linked to an increase in nitrates/nitrites and cyclic GMP levels in proximal segments. Modulation of proximal Na+, K+-ATPase activity by sodium nitroprusside was mimicked by S-nitroso-N-acetylpenicillamine (100 microM) and 8-bromo-cyclic GMP (100 microM). Both sodium nitroprusside and 8-bromo-cyclic GMP effects on Na+, K+-ATPase activity of proximal segments of trachea were blocked by 2 microM of KT 5823 (a cyclic GMP-dependent protein kinase inhibitor), but not by 0.5 microM of KT 5720 (a cyclic AMP-dependent protein kinase inhibitor). Both kinase inhibitors decreased proximal Na+, K+-ATPase activity, but did not change Mg-ATPase activity. Okadaic acid (1 microM), a phosphatase-1 inhibitor, increased proximal Na+, K+-ATPase but not Mg-ATPase activity. The effect of okadaic acid was non-additive with that of 8-bromo-cGMP on Na+, K+-ATPase activity. Our results suggest that NO modulates proximal rat trachea Na+, K+-ATPase activity through cyclic GMP and cyclic GMP-dependent protein kinase.     

Ligand effects on membrane lipids associated with sodium, potassium-activated adenosine triphosphatase: comparative spin probe studies with rat brain and heart enzyme preparations

Physical properties of membrane lipids associated with rat or dog brain and heart Na+, K+-ATPase preparations were compared using an electron spin resonance probe, 5-doxyl stearate. The degree of acyl chain order of the membrane lipids was greater for brain enzyme than for heart enzyme preparations; membrane lipids in the rat heart enzyme preparations were the most disordered. In the absence of added ligands, membrane lipids did not appear to undergo a detectable temperature-dependent rearrangement or structural transition. An apparent transition was observed in the simultaneous presence of Na+, Mg2+, and ATP. These ligands increased lipid order at temperatures above the structural transition, but not below it. In the presence of the above ligands, K+ caused a marked decrease in the transition temperature in the rat brain enzyme preparations, but only a modest decrease in rat heart enzyme preparations. Arrhenius plots of rat brain and heart Na+, K+-ATPase activity revealed a break point roughly corresponding to respective membrane lipid transition temperatures observed in the presence of Na+, K+, Mg2+, and ATP. A low concentration of ouabain (1 microM) failed to affect either the lipid transition temperature estimated by the spin probe or the value of lipid order of the rat brain enzyme preparations observed in the presence of Na+, Mg2+, and ATP, but markedly reduced the effect of K+ to lower the transition temperature observed in the presence of the above ligands. A high concentration (100 microM) of ouabain which was needed to completely inhibit rat heart enzyme eliminated the thermally induced structural rearrangement observed in the presence of Na+, Mg2+, and ATP, apparently through a nonspecific lipid perturbation. These results indicate that differences in the physical properties of the membrane lipids per se are unlikely to account for the low affinity of rat heart Na+, K+-ATPase for ouabain and also suggest that the use of high concentrations of ouabain required to completely inhibit Na+, K+-ATPase activity may cause nonspecific changes in addition to inhibition of Na+, K+-ATPase or the sodium pump.     

多巴胺对大鼠纹状体突触前和突触后膜 Na+,K+-ATP 酶活性调节的差异

用蔗糖-Ficol梯度不连续离心法制备大鼠纹状体突触前膜和突触后膜,研究多巴胺(DA)受体对突触前和突触后膜Na⁺,K⁺-ATP酶活性的调节作用。结果表明,DA(10^-8～10^-5mol·L^-1)显著抑制突触后膜Na⁺,K⁺-ATP酶的活性,单独用选择性D1(SKF38393)或D2(LY171555)受体激动剂均无抑制作用,而当二者合用时则产生与DA相似的抑制效应。DA对Na⁺,K⁺-ATP酶的抑制效应可被单独用选择性D1(SCH23390)或D2(spiperone)受体拮抗剂而逆转。相反,DA却能显著激活突触前膜Na⁺,K⁺-ATP酶的活性,单用spiperone即可逆转此激活效应。结果提示,突触前和突触后DA受体对Na⁺,K⁺-ATP酶的调节存在差异,可能与它们的不同生理功能有关。