Internal and external application of photodynamic sensitizers on squid giant axons

Oxford, Gerry S.; Pooler, John P.; Narahashi, Toshio

doi:10.1007/bf01868149

Cited by 46 publications

(30 citation statements)

References 34 publications

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“…The latter seemed ineffective when the sodium currents were prevented a second phase of inward current (Bostock 1982). Similarly, photosensitive effects on voltage dependent sodium channels have been reported for many other dyes such as bengale rose, eosin Y in squid axons and lobster neurons (Pooler 1972;Oxford et al 1977;Pooler and Valenzeno 1979). In the present study, a delay of the inactivation of voltage activated inward currents was corroborating these findings.…”

Section: Discussionsupporting

confidence: 81%

“…In the present study, a delay of the inactivation of voltage activated inward currents was corroborating these findings. A previous study showed that the prolongation of channel openings by MB was even more effective when applied intracellularly suggesting a site of action that is closer to the intracellular opening of the channel pore (Oxford et al 1977). This corresponds nicely to the assumed intracellular location of the inactivation gate of the voltage dependent sodium channel (see Hille 1992).…”

Section: Discussionmentioning

confidence: 94%

“…To investigate mechanisms of intracellular pathways, methylene blue (MB), a dye extensively used for intravital staining, has served as an important tool to block the guanylyl cyclase enzyme and deplete the cell of internal cGMP (Pickard et al 1991). However, a light-dependent prolongation of action potential duration by 10 µM MB as well as changes in the time course of an inward current at the node of Ranvier reveals similarities to other dyes (Pooler 1972;Martin and Jain 1993;Bostock 1982;Oxford et al 1977). Recently, ongoing discharge in unmyelinated primary afferents innervating rat skin has been observed, in vitro, when MB was applied in order to inhibit guanylyl cyclase and this could not be counteracted by the substitution of cGMP analogs (Kress et al 1994).…”

Section: Introductionmentioning

confidence: 99%

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Methylene blue induces ongoing activity in rat cutaneous primary afferents and depolarization of DRG neurons via a photosensitive mechanism

Kress¹,

Petersen

Reeh³

1997

Naunyn-Schmiedeberg's Arch Pharmacol

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The dye methylene blue is known as a blocker of guanylyl cyclase and it has been widely used to deplete cells of internal cyclic GMP. The data presented demonstrate an activation of adult rat sensory neurons by methylene blue via a photosensitive mechanism. In single fiber recordings from primary afferents of the rat skin in vitro, methylene blue, applied to the receptive field, induced discharge activity: 2/2 A beta-, 2/4 A delta- and 5/7 C-fibers showed significantly enhanced firing upon 10 microM methylene blue in the presence of light, whereas the dye was ineffective when illumination was prevented. In whole cell current clamp experiments with dissociated dorsal root ganglion neurons, 100 microM methylene blue was ineffective in the dark but evoked a membrane depolarization of 15.3 +/- 3.5 mV (n = 5) accompanied by discharge activity upon illumination. In whole cell voltage clamp experiments, methylene blue (100 microM) caused a significant slowing of the inactivation of voltage-dependent sodium currents. In addition, an inhibition of fast and slow outward currents was observed with prolonged exposure. The impeded sodium inactivation together with the blockade of potassium currents may contribute to the depolarization and discharge activity observed in primary afferents in vitro as well as in dissociated sensory neurons in culture. We therefore suggest that methylene blue studies with excitable cells or tissues need to be interpreted with caution.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Methylene blue induces ongoing activity in rat cutaneous primary afferents and depolarization of DRG neurons via a photosensitive mechanism

Kress¹,

Petersen

Reeh³

1997

Naunyn-Schmiedeberg's Arch Pharmacol

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“…In addition it was recently shown (20) that the fast inactivation of cloned mammalian A-type K+ channels including Kv1.4 and Kv3.4 expressed in Xenopus oocyte is abolished by oxidation and maintained by reducing agents like glutathione. Finally, photomodifications of squid axons produce a prolongation of action potentials due to a modification of K+ and Na+ currents (44) and H202 has been shown to inhibit the fast inactivation of Kv3.3 and Kv3.4 K+ channels (45).…”

Section: Resultsmentioning

confidence: 99%

Susceptibility of cloned K+ channels to reactive oxygen species.

Duprat

Guillemare

Romey

et al. 1995

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

179

112

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Free radical-induced oxidant stress has been implicated in a number of physiological and pathophysiological states including ischemia and reperfusion-induced dysrhythmia in the heart, apoptosis of T lymphocytes, phagocytosis, and neurodegeneration. We have studied the effects of oxidant stress on the native K+ channel from T lymphocytes and on K+ channels cloned from cardiac, brain, and Tlymphocyte cells and expressed in Xenopus oocytes. The activity of three Shaker K+ channels (Kvl.3, Kv1.4, and KvI.5), one Shaw channel (Kv3.4), and one inward rectifier K+ channel (IRK3) was drastically inhibited by photoactivation of rose bengal, a classical generator of reactive oxygen species. Other channel types (such as Shaker K+ channel Kv1.2, Shab channels Kv2.1 and Kv2.2, Shal channel Kv4.1, inward rectifiers IRKI and ROMK1, and hIsK) were completely resistant to this treatment. On the other hand tert-butyl hydroperoxide, another generator of reactive oxygen species, removed the fast inactivation processes of Kv1.4 and Kv3.4 but did not alter other channels. Xanthine/xanthine oxidase system had no effect on all channels studied. Thus, we show that different types of K+ channels are differently modified by reactive oxygen species, an observation that might be of importance in disease states.Molecular oxygen occupies an essential role in many of the metabolic processes associated with an aerobic existence. Oxidation and reduction reactions can lead to the formation of a variety of reactive oxygen species such as superoxide radicals (02), hydrogen peroxide (H202), hydroxyl radicals (OH-), or the long-lived diffusible singlet oxygen molecule (AgO2) (1, 2).These reactive oxygen species have been recently implicated in a variety of physiological and pathophysiological processes (3), such as apoptosis (for review, see ref. 4), cerebral ischemia (5), neurodegeneration (6), myocardial ischemia following reperfusion (7), or with heart failure in the hypertrophic heart (8).Voltage-sensitive K+ channels play an essential role in the generation of electrical activity in both neuronal and cardiac cells (9) but are also essential transport systems in a variety of other cell types such as T lymphocytes (10)

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“…If a successful recording is not achieved on the first attempt, repeat with fresh electrodes until a recording is obtained or the tissue is disrupted to the point at which the axon is no longer visible. However, it is also important to quickly place the electrode next to the axon to minimize the amount of fluorescent exposure, which can cause phototoxicity, bleaching and may affect physiological properties of the cell [29][30][31] . Once a segment of axon is successfully suctioned into the recording electrode, recordings can be obtained for several hours.…”

Section: Discussionmentioning

confidence: 99%

Retrograde Fluorescent Labeling Allows for Targeted Extracellular Single-unit Recording from Identified Neurons <em>In vivo</em>

Lyons-Warren

Kohashi

Mennerick

et al. 2013

JoVE

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The overall goal of this method is to record single-unit responses from an identified population of neurons. In vivo electrophysiological recordings from individual neurons are critical for understanding how neural circuits function under natural conditions. Traditionally, these recordings have been performed 'blind', meaning the identity of the recorded cell is unknown at the start of the recording. Cellular identity can be subsequently determined via intracellular 1 , juxtacellular 2 or loose-patch 3 iontophoresis of dye, but these recordings cannot be pre-targeted to specific neurons in regions with functionally heterogeneous cell types. Fluorescent proteins can be expressed in a cell-type specific manner permitting visuallyguided single-cell electrophysiology [4][5][6] . However, there are many model systems for which these genetic tools are not available. Even in genetically accessible model systems, the desired promoter may be unknown or genetically homogenous neurons may have varying projection patterns. Similarly, viral vectors have been used to label specific subgroups of projection neurons 7 , but use of this method is limited by toxicity and lack of trans-synaptic specificity. Thus, additional techniques that offer specific pre-visualization to record from identified single neurons in vivo are needed. Pre-visualization of the target neuron is particularly useful for challenging recording conditions, for which classical single-cell recordings are often prohibitively difficult [8][9][10][11] . The novel technique described in this paper uses retrograde transport of a fluorescent dye applied using tungsten needles to rapidly and selectively label a specific subset of cells within a particular brain region based on their unique axonal projections, thereby providing a visual cue to obtain targeted electrophysiological recordings from identified neurons in an intact circuit within a vertebrate CNS.The most significant novel advancement of our method is the use of fluorescent labeling to target specific cell types in a non-genetically accessible model system. Weakly electric fish are an excellent model system for studying neural circuits in awake, behaving animals 12 . We utilized this technique to study sensory processing by "small cells" in the anterior exterolateral nucleus (ELa) of weakly electric mormyrid fish. "Small cells" are hypothesized to be time comparator neurons important for detecting submillisecond differences in the arrival times of presynaptic spikes 13 . However, anatomical features such as dense myelin, engulfing synapses, and small cell bodies have made it extremely difficult to record from these cells using traditional methods 11,14 . Here we demonstrate that our novel method selectively labels these cells in 28% of preparations, allowing for reliable, robust recordings and characterization of responses to electrosensory stimulation. Video LinkThe video component of this article can be found at https://www.jove.com/video/3921/ Protocol 1. Prepare Dye-coated Needles 1. Electrolyt...

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Internal and external application of photodynamic sensitizers on squid giant axons

Cited by 46 publications

References 34 publications

Methylene blue induces ongoing activity in rat cutaneous primary afferents and depolarization of DRG neurons via a photosensitive mechanism

Methylene blue induces ongoing activity in rat cutaneous primary afferents and depolarization of DRG neurons via a photosensitive mechanism

Susceptibility of cloned K+ channels to reactive oxygen species.

Retrograde Fluorescent Labeling Allows for Targeted Extracellular Single-unit Recording from Identified Neurons <em>In vivo</em>

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