粉防己碱对离体大鼠心脏钙反常的保护作用

粉防己碱(Tet)能明显抑制离体大鼠心脏钙反常时心肌组织LDH和蛋白的释出,减少无钙灌流时心肌组织Ca²⁺丢失和Na⁺堆积以及复钙灌流时心肌组织Ca²⁺,Na⁺堆积和Mg²⁺,K⁺丢失,并呈浓度依赖性。此外,钙反常时心肌组织中微量元素Fe,Zn含量下降,Cu含量增加,而Tet可抑制Fe及Zn含量的下降。维拉帕米(Ver)也有类似作用,电镜下,Tet可部分减轻钙反常时心肌组织超微结构的破坏。     

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。     

α-青心酮对损伤的脑线粒体Na+,K+-ATPase活性和脑细胞耗氧的作用

目的研究α-青心酮对抗坏血酸和硫酸亚铁诱导脑线粒体Na⁺，K⁺-ATPase活性和脑细胞耗氧的作用。方法采用无机磷法测定Na⁺，K⁺-ATPase活性,分光光度法检测脑线粒体膨胀和脂质过氧化物，氧电极法测定脑细胞耗氧量。结果在抗坏血酸和硫酸亚铁的作用下，鼠脑线粒体Na⁺，K⁺-ATPase活性降低，线粒体膨胀和脑细胞脂质过氧化物升高。α-青心酮抑制其抗坏血酸和硫酸亚铁诱导脑线粒体和细胞的损伤,增加Na⁺，K⁺-ATPase活性，降低脑线粒体膨胀和脑细胞脂质过氧化物生成。α-青心酮还具有减少ADP刺激的脑细胞耗氧的作用。结论α-青心酮通过清除自由基和抗氧化作用保护脑细胞结构和功能的完整。     

丙泊酚对大鼠脑突触体Na+, K+-ATP酶和Ca2+-ATP酶活性的影响

Effect of propofol on Na⁺, K⁺-ATPase and Ca²⁺-ATPase activities of cerebral synaptosomes was investigated in rats. It was found that propfol 50 mg·kg^-1 ip significantly inhibited Na⁺, K⁺-ATPase activity of hippocampal and brain stem′s synaptosomes (P<0.01). Propofol 100 mg·kg^-1 ip significantly reduced Na⁺, K⁺-ATPase and Ca²⁺-ATPase activity of cerebrocortical, brain stem′s and hippocampal synaptosomes (P<0.01). It is suggested that the central inhibitory effect of propofol may be related to the inhibition of Na⁺, K⁺-ATPase and Ca²⁺-ATPase activity of cerebral synaptosomes.     

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。     

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。     

毒毛旋花子苷元对豚鼠心室肌细胞内钙浓度的影响

观察毒毛旋花子苷元(strophanthidin, Str)对分离豚鼠心室肌细胞内游离钙浓度(［Ca²⁺］_i)的影响。酶解分离豚鼠心室肌细胞, 用Fluo 3-AM负载, 激光共聚焦显微镜法测定单个豚鼠心室肌细胞［Ca²⁺］_i的荧光密度。Str可浓度依赖性地升高［Ca²⁺］_i, Str (10 μmol·L^-1)在［Ca²⁺］_i升高达峰值时, 可使细胞挛缩, 而Str (1和10 nmol·L^-1)对细胞形态无影响。TTX、 尼索地平或升高细胞外钙可影响Str (1和100 nmol·L^-1)对［Ca²⁺］_i的升高作用,而对Str (10 μmol·L^-1)无明显影响。在外液中加入ryanodine或去除细胞外钙, 则3个检测浓度的Str升高［Ca²⁺］_i作用均被明显抑制。在无K⁺、 无Na⁺液中, 10 μmol·L^-1 Str升高［Ca²⁺］_i的作用减弱, 而Str (1和100 nmol·L^-1)升高［Ca²⁺］_i的作用无明显影响。加入TTX、 尼索地平或增加细胞外的钙离子浓度, 则3个检测浓度Str的作用均受到影响。提示低浓度Str对［Ca²⁺］_i的升高作用与抑制Na⁺、K⁺-ATP酶活性无关, 而与促进L-型钙通道和TTX敏感性钠通道的“slip-mode”钙电导有关; 高浓度Str升高［Ca²⁺］_i的作用则是抑制Na⁺、K⁺-ATP酶的结果。此外, Str对［Ca²⁺］_i的升高作用还与直接作用于ryanodine受体促进内钙释放有关。     

间硝苯地平对老龄肾性高血压大鼠心肌和脑微粒体Na+,K+-ATP酶,Ca2+-ATP酶和Mg2+-ATP酶活性的影响

间硝苯地平(m-Nif,ig20mg·kg^-1·d^-1持续给药9周)可显著降低老龄肾性高血压大鼠(RVHR)血压和左室重量(P<0.01),增高心、脑微粒体Na⁺,K⁺-ATP酶和Ca²⁺-ATP酶活性(P<0.01),降低Mg²⁺-ATP酶活性,体外量效关系研究发现,m-Nif在较高剂量(10～1000μmol·L^-1)时可增高RVHR心脑微粒体Na⁺,K⁺-ATP酶和Ca²⁺-ATP酶活性,且随剂量增加而增高。上述结果表明,m-Nif可改善老龄RVHR心脑微粒体Na⁺,K⁺泵和Ca²⁺泵功能。     

Inhibitory effects of class I and IV antiarrhythmic drugs on the Na+-activated K+ channel current in guinea pig ventricular cells

Recently we have reported that class III antiarrhythmic drugs including amiodarone inhibit the Na⁺-activated K⁺ (K_Na) channels in isolated cardiac cells. In this study effects of antiarrhythmic drugs having class I and/or IV properties on the single K_Na channel current were examined in inside-out membrane patches of guinea pig ventricular cells by using patch clamp techniques. The K_Na channel current, which was activated by increasing [Na⁺]_i from 0 mM to 100 mM in the presence of 150 mM [K⁺]_o, showed a large slope conductance (212 pS) and inward-going rectification. Quinidine (100 μM), mexiletine (100 μM) and flecainide (10 μM) were selected as representative of class Ia, Ib and Ic drugs, respectively. These drugs at relatively high concentrations incompletely inhibited the K_Na channel by decreasing the open time (flickering block). The class IV drug verapamil inhibited the K_Na channel current mainly by decreasing the open probability although the IC₅₀ value of verapamil (3.36 μM) was higher than the therapeutic concentrations. Bepridil and SD-3212, antiarrhythmic drugs having both class I and IV properties, potently inhibited the K_Na channel current by decreasing the open probability. The IC₅₀ values of bepridil and SD-3212 for inhibiting the K_Na channel current was 0.51 μM and 0.53 μM, respectively, both of which are within the therapeutic range. Most antiarrhythmic drugs inhibit cardiac K_Na channels by different modes and at different concentrations. The K_Na channel blocking action of bepridil and SD-3212 may partly contribute to the prolongation of the action potential duration by these drugs at rapid stimulation rates. Received: 20 April 1998 / Accepted: 16 September 1998     

羟苯氨酮强心作用的生化机理研究

目的：研究羟苯氨酮(oxyphenamone, Oxy)强心作用的生化机理。方法：采用Na⁺,K⁺-ATP酶活性和cAMP-PDE活性、肌浆网Ca²⁺-ATP酶活性和cAMP含量以及心肌肌原纤维Ca²⁺,Mg²⁺-ATP酶活性等测定法,研究Oxy对它们的影响,并与milrinone和MCI-154作比较。 结果：Oxy对Na⁺,K⁺-ATP酶和PDE无抑制作用,也不影响心肌cAMP含量,但能显著增强心肌肌原纤维对Ca²⁺的敏感性,高浓度时轻度抑制心肌肌浆网Ca²⁺-ATP酶活性。结论：Oxy的强心作用方式不同于强心苷、β受体激动剂和PDE抑制剂等强心药,可能为一种新的钙增敏性强心药物。     

Mechanism of inhibition of sodium- and potassium-dependent adenosine triphosphatase by the isoquinoline derivative BIIA: a specific interaction with sodium activation

An isoquinoline derivative, 3-benzylamino-5,6-dihydro-8,9-dimethoxy-imidazo-(5,1-a)-iso-quinoline hydrochloride, BIIA, with positive inotropic and antiarrhythmic actions, reversibly inhibited the Na⁺, K⁺-ATPase of deoxycholate and NaI treated musomes from guinea-pig heart, brain and kidney. The inhibition was pH dependent, increasing with increasing pH and the concentration of the highly lipid soluble, unprotonated molecule. BIIA inhibited Na⁺, K⁺-ATPase in a concentration range of 1–100 μmoles/l, in a manner uncompetitive with respect to ATP and K⁺, and competitive with respect to Na⁺, K⁺PNPPase of the same preparation was also inhibited by BIIA, albeit at higher concentrations. This inhibition was competitive with K⁺. Affinity for substrate, as measured with [¹⁴C]-ATP, was increased and labelling from AT³²P decreased competitive with Na⁺. BIIA decreases the affinity of the enzyme for (Mg²⁺ + P_i) supported ouabain binding, higher concentrations of BIIA also affect (Na⁺ ATP) supported binding. It is suggested that BIIA enters a hydrophobic environment of the Na⁺, K⁺-ATPase and interacts at or near the Na⁺-activation sites, inhibiting the formation of the phosphorylated intermediate.     

Effects of methionine sulfoximine on cerebral ATPase

Hyperammonemia inducing drug, l-methionine-dl-sulfoximine (MSI), was administered to rats and the changes in the activities of Na⁺-ATPase and Mg²⁺-ATPase were followed in three different brain regions. The activity of Mg²⁺-ATPase decreased over the control, while that of Na²⁺, K⁺-ATPase increased in all regions. The per cent increase was more in brain stem (BS) than in cerebral cortex (CC) and cerebellum (CE). In vitro addition of MSI and ammonium chloride also resulted in similar changes. These results indicate that MSI induced toxicity is not only due to inhibition of glutamine synthetase but also by stimulation of Na⁺, K⁺-ATPase leading to the depletion of cerebral ATP levels.     

Effects of aldehydes on sodium plus potassium ion-stimulated adenosine triphosphatase of mouse brain.

The biogenic aldehydes, 3,4-dihydroxyphenylglycolaldehyde and 3,4-dihydroxyphenylacetal-dehyde, derived from norepinephrine and dopamine, respectively, as well as acetaldehyde, porpionalde-hyde, benzaldehyde and phenylacetaldehyde, inhibited both Na⁺ + K⁺-activated ATPase and Mg²⁺-ATPase. In addition, K⁺ ion-dependent p-nitrophenylphosphatase activity was inhibited by these compounds. The Na⁺ + K⁺-ATPase was much more sensitive than Mg²⁺-ATPase of K⁺-activated phosphatase to inhibition by various aldehydes. The inhibition of Na⁺ + K⁺-ATPase by aldehydes was reversible and was non-competitive with ATP or K⁺ as the variable substrate or activator respectively. Addition of cysteine or mercaptoethanol protected the enzymes from inhibition by aldehydes. The concentrations of aldehydes which produced marked inhibition of Na⁺ + K⁺-ATPase ranged from 2 × 10^?2 M to 6 × 10^?6 M for acetaldehyde and 3,4-dihydroxyphenylglycoladehyde respectively. All aldehydes, including acetaldehyde, were more potent inhibitors of Na⁺ + K⁺-ATPase activity than was ethanol.     

Studies on the mechanism of dog heart (Na+ + K+)-ATPase inhibition by D,L-aspartic acid and its K+ and Mg2+ salts.

d,l-aspartic acid as well as its K⁺ and Mg²⁺ salts have been found to be inhibitory to Na⁺ + K⁺)-ATPase activity of the dog heart microsomal fraction enriched with sarcolemma. According to intensity of the inhibitory effect (noncompetitive) they form the following sequel: mono-K⁺-aspartate $\text{?}\text{d,l}\text{-aspartic acid}\text{<}\text{mono-Mg}{}^{\mathrm{2+}}\text{-}\text{aspartate}\text{<}\text{mixture}$ of K⁺ and Mg²⁺-aspartate in a molar ratio of 1:1 (K⁺, Mg²⁺-ASP). The latter mixture is widely used as an agent in cardiac failure. For (Na⁺ + K⁺)-ATPase the salient effects of d,l-aspartic acid and/or its K⁺ and Mg²⁺ salts were: (i) decrease in V for ATP as substrate with unchanged K_m; (ii) for Na⁺ as an allosteric modifier of (Na⁺ + K⁺)-ATPase activity a decrease in V without any alteration in n as a measure of cooperativity between activating sites; (iii) for K⁺ a decrease in V and n as well as an increase in K_0.5. In the presence of Na⁺ and ATP the high affinity of the enzyme for K⁺ became reduced by d,l-aspartic acid, lowering at the same time the K_0.5 value.Effects like these have also been described for ouabain. The present data show that K⁺ and Mg²⁺ salts of d,l-aspartic acid act at a similar locus as does ouabain.     

Stimulation of Na+,K+-ATPase of isolated smooth muscle membranes by the Ca2+ channel inhibitors,nimodipine and nitrendipine

Nimodipine (0.015 to 1.5 μM) increased Na⁺, K⁺-ATPase activity by 70–120% in isolated smooth muscle membranes. At 0.015 μM, nitrendipine, but not nifedipine, verapamil or diltiazem, also activated this enzyme. Nimodipine stimulated this Na⁺, K⁺ATPase three times more than nitrendipine at 15 nM. Marked stimulation of Na⁺,K⁺-ATPase by nimopidine was seen in membranes from rat and guinea pig aorta and rat vas deferens, but not in membranes from guinea pig heart or brain. Although it is not known whether these results are applicable to intact cells, the results are consistent with the hypothesis that vasodilation produced by nimodipine and nitrendipine may be due not only to inhibition of Ca²⁺ entry but also to the stimulation of the Na^? pump.     

Changes in urinary ion excretion and related renal enzyme activities in fluoride-treated rats

Fluoride (NaF, 50 mg/kg po) administration to rats caused an increased urinary excretion of inorganic phosphate, calcium, magnesium, potassium, and sodium associated with polyuria. The renal enzyme activities of Na⁺ and K⁺-stimulated adenosine triphosphatase [(Na⁺ + K⁺)-ATPase], Mg²⁺ and Ca²⁺-stimulated adenosine triphosphatase [(Mg²⁺ + Ca²⁺)-ATPase], acid phosphatase, and alkaline phosphatase were decreased by single oral doses of fluoride. A decrease in renal (Na⁺ + K⁺)-ATPase activity was associated with an increase in urine volume and a decrease in serum sodium concentration.     

Enhancing the potency of lithospermate B for inhibiting Na+/K+-ATPase activity by forming transition metal ion complexes

Aim:

To determine whether replacing Mg²⁺ in magnesium lithospermate B (Mg-LSB) isolated from danshen (Salvia miltiorrhiza) with other metal ions could affect its potency in inhibition of Na⁺/K⁺-ATPase activity.

Methods:

Eight metal ions (Na⁺, K⁺, Mg²⁺, Cr³⁺, Mn²⁺, Co²⁺, Ni²⁺, and Zn²⁺) were used to form complexes with LSB. The activity of Na⁺/K⁺-ATPase was determined by measuring the amount of inorganic phosphate (Pi) liberated from ATP. Human adrenergic neuroblastoma cell line SH-SY5Y was used to assess the intracellular Ca²⁺ level fluctuation and cell viability. The metal binding site on LSB and the binding mode of the metal-LSB complexes were detected by NMR and visible spectroscopy, respectively.

Results:

The potencies of LSB complexed with Cr³⁺, Mn²⁺, Co²⁺, or Ni²⁺ increased by approximately 5 times compared to the naturally occurring LSB and Mg-LSB. The IC₅₀ values of Cr-LSB, Mn-LSB, Co-LSB, Ni-LSB, LSB, and Mg-LSB in inhibition of Na⁺/K⁺-ATPase activity were 23, 17, 26, 25, 101, and 128 μmol/L, respectively. After treatment of SH-SY5Y cells with the transition metal-LSB complexes (25 μmol/L), the intracellular Ca²⁺ level was substantially elevated, and the cells were viable for one day. The transition metals, as exemplified by Co²⁺, appeared to be coordinated by two carboxylate groups and one carbonyl group of LSB. Titration of LSB against Co²⁺ demonstrated that the Co-LSB complex was formed with a Co²⁺:LSB molar ratio of 1:2 or 1:1, when [Co²⁺] was less than half of the [LSB] or higher than the [LSB], respectively.

Conclusion:

LSB complexed with Cr³⁺, Mn²⁺, Co²⁺, or Ni²⁺ are stable, non-toxic and more potent in inhibition of Na⁺/K⁺-ATPase. The transition metal-LSB complexes have the potential to be superior substitutes for cardiac glycosides in the treatment of congestive heart failure.     

The Influence of Potassium Concentration on the Inhibitory Effect of Amiodarone on Guinea-Pig Microsomal Na+-K+-ATPase Activity

Abstract: The effects of varying incubation K⁺ concentration on the inhibitory action of amiodarone on the Mg²⁺-dependent ATP hydrolysis by myocardial Na⁺-K⁺-ATPase (EC 3.6.1.3) were studied in guinea pig heart preparations. In the first part of the study, it was established that the activity of the enzyme increased with growing concentrations up to approximately 20 mM K⁺. The concentration-response relationships for amiodarone were investigated in incubation media containing 2.5, 5.0 and 10 mM K⁺ respectively. Amiodarone exhibited similar concentration-dependent inhibitory effects in the range of 0.01 nM ?80 μM at 2.5 mM, 0.13–150 μM at 5.0 mM and 0.3–700 μM at 10.0 mM K⁺. The corresponding IC50 values were 10.4 ± 3.2 μM at 2.5 mM, 28.3 ± 7.6 μM at 5.0 mM and 33.3 ± 9.2 μM at 10.0 mM K⁺, respectively. Thus, reduction in the K⁺ concentration from the “standard” 5.0 to 2.5 mM was accompanied by a significant right-to-left shift in the inhibitory potency of amiodarone, the effective concentrations being shifted from uM into nM ranges. Increasing K⁺ concentration to 10 mM on the other hand attained opposite but less remarkable effects. The results show that the in vitro inhibition of myocardial Na⁺-K⁺-ATPase activity by amiodarone is related to the K⁺ concentration of the incubation medium. These effects may be pertinent to the mechanism by which this drug interferes with the electrogenic Na⁺/K⁺ pump activity of the enzyme, thereby probably contributing to the mechanism(s) responsible for some of its cardiac actions.