Potential‐sensitive membrane association of a fluorescent dye

Woolley, G. Andrew; Kapral, Moira K.; Deber, Charles M.

doi:10.1016/0014-5793(87)80480-5

Cited by 43 publications

(32 citation statements)

References 14 publications

(16 reference statements)

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“…1, inset). A similar potential response was reported in the literature [15] for Safranine O in the presence of PC-cholesterol vesicles.…”

Section: Resultssupporting

confidence: 88%

“…Subsequent addition of VAL (second arrow) causes a sharp jump of fluorescence followed by a slower phase during which a stationary level is achieved. The potential‐induced Safranine fluorescence enhancement is due to accumulation of the lipophilic cationic dye at the negatively charged interior of the vesicular membrane [15]. At a small concentration of VAL, the fluorescence remains stable for a long time, what proves that no ion leakage occurs through the vesicular membrane.…”

Section: Resultsmentioning

confidence: 91%

“…As positive potentials were reported to induce ZER channel formation, the vesicles with a high internal K + concentration were investigated at first. To monitor a transmembrane potential, which is positive outside, several fluorescent dyes were used in the literature, including the cationic Safranine type [15–17]. To test the potential response of Safranine T, a cis ‐positive transmembrane potential was generated by diluting a stock suspension of vesicles ([KCl] int =200 mM) into KCl–NaCl solutions with different concentrations of KCl and keeping [KCl] ext +[NaCl] ext =200 mM.…”

Section: Resultsmentioning

confidence: 99%

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Voltage‐dependent interaction of the peptaibol antibiotic zervamicin II with phospholipid vesicles

Kropacheva¹,

Raap²

1999

FEBS Letters

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The effect of a transmembrane potential on ion channel formation by zervamicin II (ZER-II) was studied in a vesicular model system. The dissipation of diffusion potential caused by addition of ZER-II to small phosphatidylcholine vesicles was monitored using fluorescent (Safranine T) and optical (Oxonol YI) probes. Cis-positive potentials facilitated channel formation, while at cis-negative potentials, ion fluxes were inhibited. A potential-independent behavior of ZER-II was observed at high peptide concentrations, most likely due to its membrane modifying property.z 1999 Federation of European Biochemical Societies.

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“…1, inset). A similar potential response was reported in the literature [15] for Safranine O in the presence of PC-cholesterol vesicles.…”

Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

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Voltage‐dependent interaction of the peptaibol antibiotic zervamicin II with phospholipid vesicles

Kropacheva¹,

Raap²

1999

FEBS Letters

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“…The distribution of these structures appears to be distinct from organelles such as mitochondria and nuclei, which have been reported to retain mdr substrates. 27,[33][34][35][36][37][38] Perhaps the inability to detect DNR in these compartments is a result of the known ability of DNR to intercalate with DNA, thus quenching the fluorescent signal. 18,37 However, the intracellular distribution of DNR is most compatible with acidic endosomal/lysosomal compartments.…”

Section: Discussionmentioning

confidence: 99%

Hepatic Sequestration and Modulation of the Canalicular Transport of the Organic Cation, Daunorubicin, in the Rat

Hayes¹,

Soroka²,

Rios-Velez³

et al. 1999

Hepatology

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In contrast to organic anions, substrates for the canalicular mdr1a and b are usually organic cations and are often sequestered in high concentrations in intracellular acidic compartments. Because many of these compounds are therapeutic agents, we investigated if their sequestration could be regulated. We used isolated perfused rat liver (IPRL), isolated rat hepatocyte couplets (IRHC), and WIF-B cells to study the cellular localization and biliary excretion of the fluorescent cation, daunorubicin (DNR). Despite rapid (within 15 minutes) and efficient (G90%) cellular uptake in the IPRL, only Ϸ10% of the dose administered A major function of the liver is the uptake and biliary excretion of a variety of lipophilic compounds, including endogenous substances such as bilirubin, and exogenous substances such as xenobiotics, drugs, and toxins. Distinct transport proteins are localized on the basolateral and canalicular domains of the hepatocyte to perform this function. 1,2 Many of these transporters have been cloned from rodent and human liver, and most of the canalicular transporters are members of the adenosine triphosphate (ATP) binding cassette super gene family. [3][4][5] These transporters include the multidrug resistance-associated protein, mrp2 or cMOAT, which excretes a variety of amphipathic organic anions 6-8 ; the canalicular bile salt excretory pump (bsep), which promotes ATP-dependent transport of bile salts into bile 9-11 and may be identical with spgp, the sister of P-glycoprotein 12 ; and the P-glycoproteins, mdr1a and 1b, whose endogenous substrates are not known but which transport a variety of organic cations and toxic substances into bile. [13][14][15][16][17] Overexpression of mdr1a and b can occur in cancer cell lines and thereby contribute to resistance to a variety of chemotherapeutic agents. 18 Previous studies have established that some of these excretory transport systems are highly regulated rather than constitutive functions of the hepatocyte, and that compounds such as N 6 ,2Ј-O-dibutyryl-adenosine 3Ј,5Јcyclic monophosphate (DBcAMP) and bile salts are capable of up-regulating their transport capacity. [19][20][21][22] In contrast, inhibitors of microtubule function down-regulate these transport processes. 19,21,23 This type of regulation has been demonstrated for the fluorescent bsep substrate, cholyglycylamidofluorescein (CGamF), and for the mrp2 substrate, glutathione-Smethylfluorescein. 20,21 These findings have led to the conclusion that the plasma membrane transport proteins may also reside on intracellular pericanalicular vesicles, and that apical transport capacity may be regulated by the insertion and/or retrieval of these vesicles to or from the apical canalicular membrane. 21,22,24,25 In the present study, we examined whether the canalicular excretion of the mdr1 transport system can be regulated using the fluorescent mdr1 substrate, daunorubicin (DNR). DNR is a naturally fluorescent organic cation that is widely used as an antineoplastic agent. [26][27][28] Thus, understanding ...

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“…Safranin O (3) is a potential-sensitive dye that can detect the small amount of electrogenic transport possible in vesicular systems. 24 An alternative to fluorescence is the use of commercially available ion-selective electrodes. For example, vesicle-encapsulated chloride ions are invisible to a chloride-selective electrode but they can be detected if released by a transporter.…”

Section: Vesicle-based Methodsmentioning

confidence: 99%

Development of Synthetic Membrane Transporters for Anions

2007

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The development of low molecular weight anion transporters is an emerging topic in supramolecular chemistry. The major focus of this tutorial review is on synthetic chloride transport systems that operate in vesicle and cell membranes. The transporters alter transmembrane concentration gradients, and thus they have applications as reagents for cell biology research and as potential chemotherapeutic agents. The molecular designs include monomolecular channels, self-assembled channels and mobile carriers. Also discussed are the experimental assays that measure transport rates across model bilayer membranes.

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Potential‐sensitive membrane association of a fluorescent dye

Cited by 43 publications

References 14 publications

Voltage‐dependent interaction of the peptaibol antibiotic zervamicin II with phospholipid vesicles

Voltage‐dependent interaction of the peptaibol antibiotic zervamicin II with phospholipid vesicles

Hepatic Sequestration and Modulation of the Canalicular Transport of the Organic Cation, Daunorubicin, in the Rat

Development of Synthetic Membrane Transporters for Anions

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