Properties of the new fluorescent Na+ indicator CoroNa Green: Comparison with SBFI and confocal Na+ imaging

Meier, Silke D.; Kovalchuk, Yury; Rose, Christine R.

doi:10.1016/j.jneumeth.2006.01.009

Cited by 136 publications

(187 citation statements)

References 45 publications

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“…However, the global fluorescence decay analysis of the recorded 2P-FLIM images did not unravel Na + -dependent changes (data not shown). Although this calibration procedure has been successfully applied in living cells previously, 7,32 an appropriate drug combination for sufficient control of the Na + gradient across the plasma membrane could not be established for the cockroach salivary glands.…”

Section: Photochemical and Photobiological Sciences Papermentioning

confidence: 99%

ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy

Roder

Hille

2014

Photochem Photobiol Sci

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U n i v e r s i t ä t P o t s d a mPostprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe ; 184 Phillip Roder and Carsten Hille* Sodium ions (Na + ) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na + concentrations ([Na + ] i ), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na + -sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na + -sensitivity appropriate for recordings in living cells. The Na + -sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na + ] i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamineinduced [Na + ] i rise in cockroach salivary gland cells, which was dependent on a Na + -K + -2Cl − cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems.

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Section: Photochemical and Photobiological Sciences Papermentioning

confidence: 99%

ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy

Roder

Hille

2014

Photochem Photobiol Sci

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“…Because of this, in the majority of our analysis we did not normalize to the baseline fluorescence. In addition, the sensitivity of CoroNa is less than other Na ϩ indicators (Meier et al, 2006); therefore, to increase the signal-to-noise ratio, we performed frame scans at 15 Hz and averaged the responses across 5-10 trials. Changes in fluorescence were calculated for somatic or dendritic regions of interest.…”

Section: Confocal Imagingmentioning

confidence: 99%

“…An alternative method to estimate the relative Na ϩ channel density is to perform intracellular Na ϩ imaging with Na ϩ -sensitive dyes (Meier et al, 2006;Kole et al, 2008;Fleidervish et al, 2010). We performed whole-cell recordings from GnRH neurons and loaded them with the Na ϩ -sensitive dye CoroNa Green (500 M).…”

Section: Active and Passive Spike Propagation In Gnrh Neuron Dendritesmentioning

confidence: 99%

Initiation and Propagation of Action Potentials in Gonadotropin-Releasing Hormone Neuron Dendrites

Iremonger

Herbison²

2012

J. Neurosci.

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Gonadotropin-releasing hormone (GnRH) neurons are the final output neurons in a complex neuronal network that regulates fertility. The morphology of GnRH neuron dendrites is very different to other central neurons in that they are very long, thin, and unbranched. To study the function of these dendrites, we have used Na ϩ and Ca 2ϩ imaging in combination with dual soma and dendrite electrical recordings in brain slices from GnRH-GFP mice. Here, we show that GnRH neurons actively propagate Na ϩ spikes throughout their dendrites. Multisite dendritic recordings confirmed that these spikes were observed in one of the dendrites before the soma in the great majority of neurons tested. Na ϩ imaging experiments revealed that the initial 150 m of dendrite has a higher density of functional Na ϩ channels than more distal regions, suggesting that this region of dendrite is highly excitable and may be the site of spike initiation. Finally, we show that the depolarization from dendritic spikes opens voltage-gated Ca 2ϩ channels giving rise to dendritic Ca 2ϩ transients. Together, these findings suggest that the proximal dendrites of GnRH neurons are highly excitable and are likely to be the site of action potential initiation in these neurons.

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“…Among the limited number of Na + sensors, such as sodium-binding benzofuran isophthalate (22), Sodium Green (23), CoroNa Green/Red (24,25), and Asante NaTRIUM Green-1/2 (26), most of them are not selective for Na + over K + (22-25, 27, 28) or have a low binding affinity for Na + (with a K d higher than 100 mM) (25,(27)(28)(29)(30)(31). Furthermore, the presence of organic solvents is frequently required to achieve the desired sensitivity and selectivity for many of the Na + probes (32)(33)(34), making it difficult to study Na + under physiological conditions.…”

mentioning

confidence: 99%

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

Torabi¹,

Wu²,

McGhee³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

300

286

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Over the past two decades, enormous progress has been made in designing fluorescent sensors or probes for divalent metal ions. In contrast, the development of fluorescent sensors for monovalent metal ions, such as sodium (Na + ), has remained underdeveloped, even though Na + is one the most abundant metal ions in biological systems and plays a critical role in many biological processes. Here, we report the in vitro selection of the first (to our knowledge) Na + -specific, RNA-cleaving deoxyribozyme (DNAzyme) with a fast catalytic rate [observed rate constant (k obs ) ∼0.1 min −1 ], and the transformation of this DNAzyme into a fluorescent sensor for Na + by labeling the enzyme strand with a quencher at the 3′ end, and the DNA substrate strand with a fluorophore and a quencher at the 5′ and 3′ ends, respectively. The presence of Na + catalyzed cleavage of the substrate strand at an internal ribonucleotide adenosine (rA) site, resulting in release of the fluorophore from its quenchers and thus a significant increase in fluorescence signal. The sensor displays a remarkable selectivity (>10,000-fold) for Na + over competing metal ions and has a detection limit of 135 μM (3.1 ppm). Furthermore, we demonstrate that this DNAzyme-based sensor can readily enter cells with the aid of α-helical cationic polypeptides. Finally, by protecting the cleavage site of the Na + -specific DNAzyme with a photolabile o-nitrobenzyl group, we achieved controlled activation of the sensor after DNAzyme delivery into cells. Together, these results demonstrate that such a DNAzyme-based sensor provides a promising platform for detection and quantification of Na + in living cells.M etal ions play crucial roles in a variety of biochemical processes. As a result, the concentrations of cellular metal ions have to be highly regulated in different parts of cells, as both deficiency and surplus of metal ions can disrupt normal functions (1-4). To better understand the functions of metal ions in biology, it is important to detect metal ions selectively in living cells; such an endeavor will not only result in better understanding of cellular processes but also novel ways to reprogram these processes to achieve novel functions for biotechnological applications.Among the metal ions in cells, sodium (Na + ) serves particularly important functions, as changes in its concentrations influence the cellular processes of numerous living organisms and cells (5-8), such as epithelial and other excitable cells (9). As one of the most abundant metal ions in intracellular fluid (10), Na + affects cellular processes by triggering the activation of many signal transduction pathways, as well as influencing the actions of hormones (11). Therefore, it is important to carefully monitor the concentrations of Na + in cells. Toward this goal, instrumental analyses by atomic absorption spectroscopy (12), Xray fluorescence microscopy (13), and 23 Na NMR (14) have been used to detect the concentration of intracellular Na + . However, it is difficult to use these methods to o...

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Properties of the new fluorescent Na+ indicator CoroNa Green: Comparison with SBFI and confocal Na+ imaging

Cited by 136 publications

References 45 publications

ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy

ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy

Initiation and Propagation of Action Potentials in Gonadotropin-Releasing Hormone Neuron Dendrites

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

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