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INHIBITION OF DENITRIFICATION BY UNCOUPLERS OF OXIDATIVE-PHOSPHORYLATION

BIOCHEMISTRY 1978年第15期17卷 3039-3045页

作者： WALTER, B SIDRANSKY, E KRISTJANSSON, JK HOLLOCHER, TC BRANDEIS UNIV DEPT BIOCHEM WALTHAM MA 02154 USA

In the denitrifiers, Pseudomonas denitrificans and P. aeruginosa, nitrogen oxide respirations were reversibly inhibited by several weak acid-type uncouplers of oxidative phosphorylation. Their effectiveness as uncouplers stood in about the same rank as their effectiveness as inhibitors. Uncouplers increased the rate of O2 respiration (release of respiratory control) in these 2 organisms and seemed not to inhibit even at rather high concentrations. The mechanism of inhibition of nitrogen oxide respiration by uncouplers was explored and several lines of evidence ruled out an inhibition which depended on collapse of the proton motive force per se. The concentrations of uncouplers required to inhibit nitrogen oxide respirations in P. denitrificans were at least 10 times higher than those required to inhibit respiration-driven amino acid uptake, to release respiratory control in the case of O2 respiration and to increase membrane proton conductivity to such levels that endergonic reactions dependent on proton motive force must, by calculation, be inhibited. Neither valinomycin/K+ (to collapse membrane potential) nor nigericin (to collapse .***) had an inhibitory effect on nitrogen oxide respirations, whether present separately or together. Nonuncoupling analogs of the nitrophenol and carbonyl cyanide phenylhydrazone uncouplers were effective in inhibiting respiration. The inhibitions are attributed in large part to the hydrophobic properties of these compounds. Spectrophotometric observations suggested that the site of inhibition lay on the reducing side of cytochromes b and c. In the steady states of nitrogen oxide respirations, cytochromes b and c remained nearly completely oxidized in the presence of u;ncouplers, and the transition from steady state to reduced state upon the exhaustion of nitrogen oxide was inhibited. Certain trivial explanations for the inhibitory effect of uncouplers, such as substrate starvation, were ruled out.

关键词：碳酰氰化物对三氟甲氧苯基腙/药理学二环己基碳二亚胺/药理学二硝基酚类/药理学动力学尼日利亚菌素/药理学氧化氮类/代谢氧耗量/药物作用假单胞菌属/药物作用假单胞菌属/代谢铜绿假单胞菌/药物作用铜绿假单胞菌/代谢解偶联药/药理学缬氨霉素/药理学

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LLC-PK₁ cells stably expressing the human norepinephrine transporter:: A functional model of carrier-mediated norepinephrine release in protracted myocardial ischemia

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JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS 1999年第2期291卷 456-463页

作者： Smith, NCE Levi, R Cornell Univ Weill Med Coll Dept Pharmacol New York NY 10021 USA

In myocardial ischemia, adrenergic terminals undergo ATP depletion, hypoxia, and intracellular pH reduction, causing the accumulation of axoplasmic norepinephrine (NE) and intracellular Na+ [via the Na+-H+ exchanger (NHE)]. This forces the reversal of the Na+- and Cl--dependent NE transporter (NET), triggering massive carrier-mediated NE release and, thus, arrhythmias. We have now developed a cellular model of carrier-mediated NE release using an LLC-PK1 cell line stably transfected with human NET cDNA (LLC-NET). LLC-NET cells transported [H-3]NE and [H-3]N-methyl-4-phenylpyridinium ([H-3]MPP+) in an inward direction. This uptake was abolished by the NET inhibitors desipramine (100 nM) and mazindol (300 nM) and by extracellular Na+ removal. Na+-gradient reversal induced an efflux of H-3-substrate from preloaded LLC-NET cells. Desipramine and mazindol blocked this efflux. Because of its greater intracellular stability and higher sensitivity to Na+ gradient reversal, [H-3]MPP+ proved preferable to [H-3]NE as an NET substrate;therefore, only [H-3]MPP+ was used for subsequent studies. The K+/H+ ionophore nigericin (10 mu M) evoked a large efflux of [H-3]MPP+. This efflux was potentiated by the Na+,K+-ATPase inhibitor ouabain (100 mu M), was sensitive to desipramine, and was blocked by the NHE inhibitor 5-(N-ethyl-N-isopropyl)-amiloride (EIPA;10 mu M). In contrast, EIPA failed to inhibit the [H-3]MPP+ efflux elicited by the Na+ ionophore gramicidin (10 mu M). Furthermore, [H-3]MPP+ efflux induced by the NHE-stimulant proprionate (25 mM) was negatively modulated by imidazoline receptor activation. Our findings suggest that LLC- NET cells are a sensitive model for studying transductional processes of carrier-mediated NE release associated with myocardial ischemia.

关键词： 1-甲基-4-苯基吡啶/代谢阿米洛利/类似物和衍生物阿米洛利/药理学生物转运主动地昔帕明/药理学药物相互作用短杆菌肽/药理学 LLC-PK1细胞马吲哚/药理学模型生物学心肌缺血/代谢尼日利亚菌素/药理学去甲肾上腺素/分泌受体药物/代谢钠/生理学猪时间因素动物人类

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Reversible drug-induced oxyntic atrophy in rats

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GASTROENTEROLOGY 2000年第6期118卷 1080-1093页

作者： Goldenring, JR Ray, GS Coffey, RJ Meunier, PC Haley, PJ Barnes, TB Car, BD Med Coll Georgia Inst Mol Med & Genet Dept Med Augusta GA 30912 USA Med Coll Georgia Augusta Vet Affairs Med Ctr Augusta GA 30912 USA Med Coll Georgia Dept Surg Augusta GA 30912 USA Med Coll Georgia Dept Cell Biol & Anat Augusta GA 30912 USA DuPont Pharmaceut Corp Newark DE USA Vanderbilt Univ Sch Med Dept Med Nashville TN 37212 USA Vanderbilt Univ Sch Med Dept Cell Biol Nashville TN 37212 USA Cephalon W Chester PA USA

Background & Aims: Oxyntic atrophy is the hallmark of chronic gastritis, Many studies have sought to develop animal models for oxyntic atrophy, but none of them are reversible, We now report that rats administered high doses of DMP 777 demonstrate reversible oxyntic atrophy, Methods: DMP 777 was administered to CD-1 rats by oral gavage (200 mg . kg(-1) . day(-1)). Serum gastrin level, in vivo acid secretion, and gastric histological changes were evaluated in DMP 777-dosed animals. Direct effects of DMP 777 on parietal cells were evaluated by assessment of aminopyrine accumulation into isolated rabbit parietal cells, as well as by assessment of DMP 777 effects on acridine orange fluorescence and H+,K+-adenosine triphosphatase (ATPase) activity in isolated tubulovesicles, Results: Oral dosing with DMP 777 caused a rapid increase in serum gastrin levels and severe hypochlorhydria. DMP 777 inhibited aminopyrine accumulation into rabbit parietal cells stimulated with either histamine or forskolin, DMP 777 reversed a stimulated proton gradient in isolated parietal cell tubulovesicles. Oral dosing with DMP 777 led to rapid loss of parietal cells from the gastric mucosa, In response to the acute loss of parietal cells, there was an increase in the activity of the progenitor zone along with rapid expansion of the foveolar cell compartment. DMP 777 treatment also led to the emergence of bromodeoxyuridine-labeled cells and cells positive for periodic acid-Schiff in the basal region of fundic glands. With extended dosing over 3-6 months, foveolar hyperplasia and oxyntic atrophy were sustained while chief cell, enterochromaffin-like cell, and somatostatin cell populations were decreased. No histological evidence of neoplastic transformation was observed with dosing up to 6 months. Withdrawal of the drug after 3 or 6 months of dosing led to complete restitution of the normal mucosal lineages within 3 months. Conclusions: DMP 777 acts as a protonophore with specificity for parieta

关键词：吖啶橙氨基比林/药代动力学消炎药非甾类/药代动力学萎缩吖丁啶类碳放射性同位素疾病模型动物酶抑制剂/药理学荧光染料胃酸/代谢胃泌素类/血液胃炎/化学诱导胃炎/病理学 H(+)K(+)交换ATP酶/代谢离子载体/药理学白细胞弹性蛋白酶/拮抗剂和抑制剂白细胞弹性蛋白酶/代谢坏死尼日利亚菌素/药理学壁细胞胃/酶学壁细胞胃/代谢壁细胞胃/病理学哌嗪类大鼠 Sprague-Dawley 再生胃/病理学胃/生理学动物男(雄)性兔大鼠

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COMPARISON OF THE EFFECTS OF FLUORIDE AND THE IONOPHORE NIGERICIN ON ACID PRODUCTION BY STREPTOCOCCUS-MUTANS AND THE RESULTANT INVITRO ENAMEL DEMINERALIZATION

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JOURNAL OF DENTAL RESEARCH 1987年第11期66卷 1658-1662页

作者： VANLOVEREN, C FIELMICH, AM TENBRINK, B STATE UNIV UTRECHT DEPT PREVENT DENT UTRECHT NETHERLANDS

In an in vitro demineralization experiment with a plaque of S. mutans C180-2 over enamel, the effect of 0.5 mmol fluoride/L was compared with that of 10 nmol nigericin/L. Since the effects of both substances on the acid production in a dense cell suspension were of the same magnitude, and since nigericin did not affect the enamel solubility, the present demineralization experiment may differentiate between the effect of fluoride on bacterial metabolism alone and the combined effect of fluoride on both the bacterial metabolism and enamel solubility. In our experiments, the effect on bacterial metabolism accounted for 75% of the caries-inhibiting effect of *** data showed subsurface lesions in the control and nigericin group and a slight surface-softening in the fluoride group. In addition, the effects of fluoride and nigericin on the cellular internal pH during glycolysis were studied. Analysis of these data suggested that glycolysis was inhibited when the intracellular pH reached about pH 5.2, which supports the view that acidification of the cell cytoplasm is a mechanism by which fluoride inhibits glycolysis.

关键词：酸类/代谢磷酸钙类/代谢制龋药/药理学细胞质/药物作用牙釉质/药物作用牙釉质/微生物学牙釉质可溶性/药物作用牙菌斑/微生物学发酵/药物作用氟化物/药理学糖酵解/药物作用氢离子浓度离子载体/药理学 X线放大摄影术尼日利亚菌素/药理学链球菌变异/药物作用链球菌变异/代谢牙失矿质/微生物学牙失矿质/病理生理学动物牛

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EFFECT OF IONOPHORES A23187 AND NIGERICIN ON LIGHT-INDUCED REDISTRIBUTION OF MG2+,K+ AND H+ ACROSS THYLAKOID MEMBRANE

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BIOCHIMICA ET BIOPHYSICA ACTA 1976年第1期449卷 48-58页

作者： BULYCHEV, AA VREDENBERG, WJ CTR AGROBIOL RES WAGENINGEN NETHERLANDS

Passive redistributions of Mg2+ and K+ ions across the thylakoid membranes, occurring in association with the light-driven electrogenic influx of H ions were examined in suspensions of broken spinach chloroplasts under a variety of conditions. In accord with results of Hind et al, at a low K/Mg concentration ratio in the medium the K-efflux is negligibly small, whereas a substantial Mg-efflux is observed. The converse is true when the K/Mg concentration ratio in the medium is high. In the presence of A23187, which causes approximately a 60% inhibition of the light-induced pH-gradient, a significant influx of Mg2+ was observed in the light at a high K/Mg concentration ratio. Conversely the Mg-influx was small in the presence of A23187 when the K/Mg concentration ratio in the medium was low. Under these conditions, the Mg-influx was considerably increased upon the addition of valinomycin. A23187 was found not to affect the K-efflux in the light. The light-induced K-influx observed in the presence of nigericin also was dependent on the concentration ratio of the monovalent and divalent cation. Its magnitude increased upon an increase in the K/Mg ratio. The results are interpreted in terms of a simplified model in which the total passive efflux of cations, driven the potential set by the electrogenic proton pump, is considered to be a constant fraction of the proton influx. An increase in the flux of an ion species, induced by raising its concentration, or by increasing its permeability through the membrane, cause a decrease in the flux of the other cations. The relevance of the results is discussed with respect to conclusions about the involvement and relative magnitudes of the passive K and Mg effluxes across the thylakoid membrane during energization of intact chloroplasts and chloroplasts in situ.

关键词：抗菌药/药理学卡西霉素/药理学叶绿体/代谢叶绿体/辐射效应依地酸/药理学电子转运氢/代谢氢离子浓度光镁/代谢膜/辐射效应模型生物学尼日利亚菌素/药理学氧耗量钾/代谢缬氨霉素/药理学

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Isoniazid accumulation in Mycobacterium smegmatis is modulated by proton motive force-driven and ATP-dependent extrusion systems

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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 1999年第3期256卷 682-684页

作者： Choudhuri, BS Sen, S Chakrabarti, P Bose Inst Dept Chem Kolkata 700009 W Bengal India

Resistance to isoniazid (INH), a frontline, antituberculosis drug, presents a major problem in the chemotherapy of tuberculosis. Although several targets of INH have been identified, the mechanism of INH resistance remains incompletely understood. This report demonstrates that INH accumulation in Mycobacterium smegmatis is enhanced both upon addition of both a proton motive force (pmf) uncoupler, carbonyl-cyanide m-chlorophenylhydrazone (CCCP), and upon addition of ortho-vanadate, an inhibitor of ATP-dependent efflux pumps. Both the Delta psi and Delta pH components of the pmf are likely to be involved as judged by the effects of valinomycin and nigericin, respectively, Reserpine, an inhibitor of the human MDRI P-glycoprotein, enhances INH accumulation in a man ner similar too-vanadate. Verapamil, a calcium channel blocker, so enhances INH uptake. Taken together, the results provide evidence of the involvement of both pmf- and ATP-dependent extrusion systems in INH efflux in M. smegmatis, making it important to evaluate the role of such systems in INH resistance ire pathogenic mycobacteria. (C) 1999 Academic Press.

关键词：腺苷三磷酸/代谢抗结核药/代谢抗结核药/药理学生物转运主动/药物作用钙通道阻滞药/药理学碳酰氰化物间-氯苯基腙/药理学地尔硫|艹卓|/药理学抗药性微生物氢离子浓度离子载体/药理学异烟肼/代谢异烟肼/药理学分枝杆菌耻垢/药物作用分枝杆菌耻垢/生长和发育分枝杆菌耻垢/代谢硝苯地平/药理学尼日利亚菌素/药理学质子动力势/药物作用质子动力势/生理学利血平/药理学解偶联药/药理学缬氨霉素/药理学钒酸盐类/药理学维拉帕米/药理学

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Adenovirus cellular receptor site recirculation of HeLa cells upon receptor-mediated endocytosis is not low pH-dependent

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ARCHIVES OF VIROLOGY 1999年第4期144卷 787-795页

作者： Everitt, E Rodríguez, E Univ Lund Dept Microbiol SE-22362 Lund Sweden

HeLa cells were depleted of 75% of the available adenovirus type 2 specific cellular receptor sites (CRSs) by controlled attachment of viruses at a high multiplicity of infection. Upon removal of unattached viruses and further incubation, the cells were able to recycle the CRSs to 75% of the level of uninfected control cells within 5 h. The rate of virus receptor recycling was approx. 1 CRS x min(-1) x cell(-1). The existense of receptor recycling further strengthens the involvement of a total process of receptor-mediated endocytosis in adenovirus internalization. The recirculation process was neither affected by the lysosomotropic agents ammonium chloride and amantadine-HCl, nor by the ionophore monensin or the multifunctional weak-base amine chloroquine.

关键词：腺病毒人/药物作用腺病毒人/生理学金刚烷胺/药理学氯化铵/药理学氯喹/药理学放线菌酮/药理学胞吞作用 HeLa细胞氢离子浓度动力学甲硫氨酸/代谢莫能星/药理学尼日利亚菌素/药理学受体病毒/药物作用受体病毒/分离和提纯受体病毒/生理学硫放射性同位素人类

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Mutations in a tRNA import signal define distinct receptors at the two membranes of Leishmania mitochondria

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MOLECULAR AND CELLULAR BIOLOGY 2000年第19期20卷 7410-7417页

作者： Bhattacharyya, SN Mukherjee, S Adhya, S Indian Inst Chem Biol Genet Engn Lab Kolkata 700032 W Bengal India

Nucleus-encoded tRNAs are selectively imported into the mitochondrion of Leishmania, a kinetoplastid protozoan. An oligoribonucleotide constituting the D stem-loop import signal of tRNA(Tyr)(GUA) was efficiently transported into the mitochondrial matrix in organello as well as in vivo. Transfer through the inner membrane could be uncoupled from that through the outer membrane and was resistant to antibody against the outer membrane receptor TAB. A number of mutations in the import signal had differential effects on outer and inner membrane transfer. Some mutants which efficiently traversed the outer membrane mere unable to enter the matrix. Conversely, restoration of the loop-closing GC pair in reverse resulted in reversion of transfer through the inner, but not the outer, membrane, and binding of the RNA to the inner membrane was restored. These experiments indicate the presence at the two membranes of receptors with distinct specificities which mediate stepwise transfer into the mitochondrial matrix. The combination of oligonucleotide mutagenesis and biochemical fractionation may provide a general tool for the identification of tRNA transport factors.

关键词：腺苷三磷酸/药理学碱基配对生物转运主动碳酰氰化物间-氯苯基腙/药理学阳离子一价/药理学细胞内膜/代谢热带利什曼原虫/遗传学热带利什曼原虫/代谢膜蛋白质类/代谢线粒体/药物作用线粒体/代谢模型生物学诱变定点尼日利亚菌素/药理学核酸构象表型点突变蛋白质结合原虫蛋白质类/代谢 RNA 原虫/化学 RNA 原虫/遗传学 RNA 原虫/代谢 RNA 转移酪氨酸/化学 RNA 转移酪氨酸/遗传学 RNA 转移酪氨酸/代谢 RNA结合蛋白质类/代谢构效关系温度解偶联药/药理学动物

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FURTHER EVIDENCE FOR A PROTON PUMP IN MOUSE KIDNEY PHAGOLYSOSOMES - EFFECT OF NIGERICIN AND 2,4-DINITROPHENOL ON STIMULATION OF INTRALYSOSOMAL PROTEOLYSIS BY ATP

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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 1975年第2期67卷 571-575页

作者： MEGO, JL UNIV ALABAMA DEPT BIOLUNIVERSITYAL 35486

The lipid soluble acid 2,4-dinitrophenol completely abolished the stimulatory effect of ATP on intralysosomal proteolysis in mouse kidney phagolysosomes at pH 8. The protonophore had no effect in the absence of ATP at pH 8 but inhibited intralysosomal proteolysis in unbuffered media. The ionophorous antibiotic nigericin also prevented the action of ATP at pH 8 but had no effect in the absence of ATP in unbuffered media. Nigericin also inhibited intralysosomal proteolysis at pH 8 in the absence of ATP. These observations support the hypothesis that the phagolysosome membrane contains an ATP-driven proton pump which functions to maintain intralysosomal acidity.

关键词：腺苷三磷酸/药理学抗菌药/药理学二硝基酚类/药理学氢离子浓度肾/超微结构动力学溶酶体/药物作用溶酶体/酶学尼日利亚菌素/药理学肽水解酶类/代谢温度动物小鼠

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Studies on the prevention of nigericin action in neuroblastoma x glioma hybrid (NG108-15) cells

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PHARMACOLOGY & TOXICOLOGY 2000年第2期87卷 63-68页

作者： Doebler, JA USA Med Res Inst Chem Def Neurotoxicol Branch Div Pharmacol Aberdeen Proving Ground MD 21010 USA

Electrophysiological analysis of neuroblastoma X glioma hybrid (NG108-15) cells was used as an in vitro neuronal model system to evaluate antagonists of the K+-selective carboxylic ionophore, nigericin. Changes in membrane electrical characteristics induced by nigericin with and without the simultaneous administration of antagonists were measured using intracellular microelectrode techniques. Bath application of nigericin (3 mu M) produced a severe hyperpolarization and blocked the generation of action potentials in response to electrical stimulation. Simultaneous administration of nigericin plus the Na+-K+ pump inhibitor ouabain or drugs known to influence Ca++ signaling in cells, i.e., quinidine, compound R24571, verapamil or haloperidol, was able to significantly attenuate the hyperpolarization. All antagonists acted in a concentration-dependent manner. However, nigericin plus maximally effective concentrations of ouabain (1 mu M), verapamil (3 mu M) and haloperidol (3 and 10 mu M) resulted in moderate-to-severe depolarization by the end of 24 min. superfusions, suggesting that the concentrations of antagonists were excessive and that NG108-15 cell damage had occurred. In addition, none of the compounds studied was able to effectively prevent nigericin-induced blockade of action potentials. Thus, none of these antagonists appears suitable for transition to in vivo antidotal protection studies.

关键词：钙通道阻滞药/药理学电生理学酶抑制剂/药理学离子载体/拮抗剂和抑制剂离子载体/药理学膜电位/药物作用神经母细胞瘤/代谢尼日利亚菌素/拮抗剂和抑制剂尼日利亚菌素/药理学哇巴因/药理学奎尼丁/药理学肿瘤细胞培养的/药物作用维拉帕米/药理学

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