scholarly journals Artificially imposed electrical potentials drive l-glutamate uptake into synaptic vesicles of bovine cerebral cortex

1990 ◽  
Vol 267 (1) ◽  
pp. 63-68 ◽  
Author(s):  
J Shioi ◽  
T Ueda
Keyword(s):  
Cerebral Cortex ◽  
Synaptic Vesicles ◽  
Glutamate Uptake ◽  
Electrical Potential ◽  
Potential Gradient ◽  
Protonmotive Force ◽  
Uptake System ◽  
Vesicle Membrane ◽  
Excitatory Neurotransmitter ◽  
Electrical Potentials

L-Glutamate is a major excitatory neurotransmitter in the central nervous system. MgATP-dependent glutamate uptake and H(+)-pumping ATPase activity were reported in highly purified synaptic vesicles [Naito & Ueda (1983) J. Biol. Chem. 258, 696-699; Shioi, Naito & Ueda (1989) Biochem. J. 258, 499-504], and it is hypothesized that an electrochemical H+ gradient across the vesicle membrane, the so-called protonmotive force, elicits the neurotransmitter uptake. An inside-positive diffusion potential across the vesicle membrane was established with valinomycin plus Rb+. This artificial electrical potential promoted the uptake of glutamate, but not aspartate, in the synaptic vesicles prepared from bovine cerebral cortex. The uptake was inhibited by the protonmotive-force dissipators carbonyl cyanide p-trifluoro-methoxyphenylhydrazone or nigericin, and was enhanced by concomitant imposition of a pH jump (alkalinization) in the external medium. Subcellular and subvesicular distributions showed the uptake system to be predominantly associated with small synaptic vesicles. The results support the hypothesis that glutamate uptake into synaptic vesicles is coupled with a H+ efflux down the electrochemical potential gradient, which is generated by H(+)-pumping ATPase.

scholarly journals Glutamate uptake into synaptic vesicles of bovine cerebral cortex and electrochemical potential difference of proton across the membrane

1989 ◽  
Vol 258 (2) ◽  
pp. 499-504 ◽  
Author(s):  
J Shioi ◽  
S Naito ◽  
T Ueda
Keyword(s):  
Cerebral Cortex ◽  
Synaptic Vesicles ◽  
Driving Force ◽  
Significant Contribution ◽  
Atp Hydrolysis ◽  
Glutamate Uptake ◽  
Protonmotive Force ◽  
Chromaffin Granule ◽  
Carbonyl Cyanide ◽  
Disulphonic Acid

Measurements have been made of the ATP-dependent membrane potential (delta psi) and pH gradient (delta pH) across the membranes of the synaptic vesicles purified from bovine cerebral cortex, using the voltage-sensitive dye bis[3-propyl-5-oxoisoxazol-4-yl]pentamethine oxanol and the delta pH-sensitive fluorescent dye 9-aminoacridine respectively. A pre-existing small delta pH (inside acidic) was detected in the synaptic vesicles, but no additional significant contribution by MgATP to delta pH was observed. In contrast, delta psi (inside positive) increased substantially upon addition of MgATP. This ATP-dependent delta psi was reduced by thiocyanate anion (SCN-), a delta psi dissipator, or carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), a protonmotive-force dissipator. Correspondingly, a substantially larger glutamate uptake occurred in the presence of MgATP, which was inhibited by SCN- and FCCP. A nonhydrolysable analogue of ATP, adenosine 5′-[beta gamma-methylene]triphosphate, did not substitute for ATP in either delta psi generation or glutamate uptake. The results support the hypothesis that a H+-pumping ATPase generates a protonmotive force in the synaptic vesicles at the expense of ATP hydrolysis, and the protonmotive force thus formed provides a driving force for the vesicular glutamate uptake. The delta psi generation by ATP hydrolysis was not affected by orthovanadate, ouabain or oligomycin, but was inhibited by N-ethylmaleimide, quercetin, trimethyltin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole and 4-acetamido-4′-isothiocyanostilbene-2,2′-disulphonic acid. These results indicate that the H+-pumping ATPase in the synaptic vesicle is similar to that in the chromaffin granule, platelet granule and lysosome.

scholarly journals Peroxidase uptake by photoreceptor terminals of the skate retina.

1976 ◽  
Vol 70 (1) ◽  
pp. 86-96 ◽  
Author(s):  
H Ripps ◽  
M Shakib ◽  
E D MacDonald
Keyword(s):  
Transmitter Release ◽  
Synaptic Vesicles ◽  
Light Adaptation ◽  
Ringer Solution ◽  
Bathing Solution ◽  
Synaptic Terminal ◽  
Vesicle Membrane ◽  
Electrical Potentials ◽  
Membrane Bound ◽  
Peroxidase Uptake

The photoreceptors of dark-adapted skate retinas bathed in a Ringer solution containing horseradish peroxidase (HRP) incorporate the tracer into membrane-bound compartments within the synaptic terminal of the cell; after 1 or 2 h of incubation, approx. 10-38% of the synaptic vesicles were labeled. The receptors appeared to be functioning normally throughout the incubation period, since electrical potentials of normal amplitude could be elicited in response to dimphotic stimuli. However, it was possible to block the uptake of peroxidase by a regimen of light adaptation that effectively suppressed light-induced activity in the electroretinogram. If, during incubation with peroxidase, retinas were exposed at 10-min intervals to an intense 1-ms flash from a xenon discharge tube, the receptor terminals were almost completely devoid of peroxidase; fewer than 2% of the vesicles were labeled. The suppression of HRP uptake could also be achieved in dark-adapted retinas by adding magnesium to the bathing solution, suggesting that calcium is necessary for transmitter release from vesicles in the receptor terminals. These findings are consistent with the view that vertebrate photoreceptors discharge a neurotransmitter in darkness, and that light decreases the release of this substance. It seems likely that the incorporation of peroxidase into vesicles of physiologically active receptor terminals reflects a mechanism for the retrieval of vesicle membrane after exocytosis.

scholarly journals Rapid changes in synaptic vesicle cytochemistry after depolarization of cultured cholinergic sympathetic neurons.

1985 ◽  
Vol 101 (1) ◽  
pp. 217-226 ◽  
Author(s):  
M I Johnson ◽  
K Paik ◽  
D Higgins
Keyword(s):  
Synaptic Vesicles ◽  
Sympathetic Neurons ◽  
Uptake System ◽  
Vesicle Membrane ◽  
Vesicle Release ◽  
Cholinergic Function ◽  
Dense Cores ◽  
Amine Storage ◽  
Rapid Changes ◽  
Cervical Ganglia

Sympathetic neurons taken from rat superior cervical ganglia and grown in culture acquire cholinergic function under certain conditions. These cholinergic sympathetic neurons, however, retain a number of adrenergic properties, including the enzymes involved in the synthesis of norepinephrine (NE) and the storage of measurable amounts of NE. These neurons also retain a high affinity uptake system for NE; despite this, the majority of the synaptic vesicles remain clear even after incubation in catecholamines. The present study shows, however, that if these neurons are depolarized before incubation in catecholamine, the synaptic vesicles acquire dense cores indicative of amine storage. These manipulations are successful when cholinergic function is induced with either a medium that contains human placental serum and embryo extract or with heart-conditioned medium, and when the catecholamine is either NE or 5-hydroxydopamine. In some experiments, neurons are grown at low densities and shown to have cholinergic function by electrophysiological criteria. After incubation in NE, only 6% of the synaptic vesicles have dense cores. In contrast, similar neurons depolarized (80 mM K+) before incubation in catecholamine contain 82% dense-cored vesicles. These results are confirmed in network cultures where the percentage of dense-cored vesicles is increased 2.5 to 6.5 times by depolarizing the neurons before incubation with catecholamine. In both single neurons and in network cultures, the vesicle reloading is inhibited by reducing vesicle release during depolarization with an increased Mg++/Ca++ ratio or by blocking NE uptake either at the plasma membrane (desipramine) or at the vesicle membrane (reserpine). In addition, choline appears to play a competitive role because its presence during incubation in NE or after reloading results in decreased numbers of dense-cored vesicles. We conclude that the depolarization step preceding catecholamine incubation acts to empty the vesicles of acetylcholine, thus allowing them to reload with catecholamine. These data also suggest that the same vesicles may contain both neurotransmitters simultaneously.

Effects of methylmalonic and propionic acids on glutamate uptake by synaptosomes and synaptic vesicles and on glutamate release by synaptosomes from cerebral cortex of rats

2001 ◽  
Vol 920 (1-2) ◽  
pp. 194-201 ◽  
Author(s):  
Ana Maria Brusque ◽  
Liane Nanci Rotta ◽  
Rejane Giacomelli Tavares ◽  
Tatiana Emanuelli ◽  
Carolina Vargas Schwarzbold ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Synaptic Vesicles ◽  
Glutamate Uptake ◽  
Glutamate Release

scholarly journals The strain-generated electrical potential in cartilaginous tissues: a role for piezoelectricity

2021 ◽  
Vol 13 (1) ◽  
pp. 91-100
Author(s):  
Philip Poillot ◽  
Christine L. Le Maitre ◽  
Jacques M. Huyghe
Keyword(s):  
Physiological Response ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Electrical Potential ◽  
Evidence Base ◽  
Piezoelectric Response ◽  
Mechanical Forces ◽  
Streaming Potentials ◽  
Cartilaginous Tissues ◽  
Electrical Potentials

AbstractThe strain-generated potential (SGP) is a well-established mechanism in cartilaginous tissues whereby mechanical forces generate electrical potentials. In articular cartilage (AC) and the intervertebral disc (IVD), studies on the SGP have focused on fluid- and ionic-driven effects, namely Donnan, diffusion and streaming potentials. However, recent evidence has indicated a direct coupling between strain and electrical potential. Piezoelectricity is one such mechanism whereby deformation of most biological structures, like collagen, can directly generate an electrical potential. In this review, the SGP in AC and the IVD will be revisited in light of piezoelectricity and mechanotransduction. While the evidence base for physiologically significant piezoelectric responses in tissue is lacking, difficulties in quantifying the physiological response and imperfect measurement techniques may have underestimated the property. Hindering our understanding of the SGP further, numerical models to-date have negated ferroelectric effects in the SGP and have utilised classic Donnan theory that, as evidence argues, may be oversimplified. Moreover, changes in the SGP with degeneration due to an altered extracellular matrix (ECM) indicate that the significance of ionic-driven mechanisms may diminish relative to the piezoelectric response. The SGP, and these mechanisms behind it, are finally discussed in relation to the cell response.

Synaptic vesicles immunoisolated from rat cerebral cortex contain high levels of glutamate

Neuron ◽  
1989 ◽  
Vol 3 (6) ◽  
pp. 715-720 ◽  
Author(s):  
Peter M. Burger ◽  
Ehrenfried Mehl ◽  
Patricia L. Cameron ◽  
Peter R. Maycox ◽  
Marion Baumert ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Synaptic Vesicles ◽  
Rat Cerebral Cortex

Understanding the electrical behavior of the action potential in terms of elementary electrical sources

2015 ◽  
Vol 39 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Javier Rodriguez-Falces
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Present Report ◽  
Electrical Potential ◽  
Ionic Currents ◽  
New Approach ◽  
Electrical Potentials ◽  
Proposed Model ◽  
Ionic Mechanisms ◽  
Human Electrophysiology

A concept of major importance in human electrophysiology studies is the process by which activation of an excitable cell results in a rapid rise and fall of the electrical membrane potential, the so-called action potential. Hodgkin and Huxley proposed a model to explain the ionic mechanisms underlying the formation of action potentials. However, this model is unsuitably complex for teaching purposes. In addition, the Hodgkin and Huxley approach describes the shape of the action potential only in terms of ionic currents, i.e., it is unable to explain the electrical significance of the action potential or describe the electrical field arising from this source using basic concepts of electromagnetic theory. The goal of the present report was to propose a new model to describe the electrical behaviour of the action potential in terms of elementary electrical sources (in particular, dipoles). The efficacy of this model was tested through a closed-book written exam. The proposed model increased the ability of students to appreciate the distributed character of the action potential and also to recognize that this source spreads out along the fiber as function of space. In addition, the new approach allowed students to realize that the amplitude and sign of the extracellular electrical potential arising from the action potential are determined by the spatial derivative of this intracellular source. The proposed model, which incorporates intuitive graphical representations, has improved students' understanding of the electrical potentials generated by bioelectrical sources and has heightened their interest in bioelectricity.

scholarly journals Activity and cytosolic Na+ regulates synaptic vesicle endocytosis

2019 ◽  
Author(s):  
Yun Zhu ◽  
Dainan Li ◽  
Hai Huang
Keyword(s):  
Synaptic Transmission ◽  
High Frequency ◽  
Synaptic Vesicles ◽  
Glutamate Uptake ◽  
High Frequencies ◽  
Vesicle Recycling ◽  
Two Photon ◽  
Readily Releasable Pool ◽  
Content Change ◽  
Intracellular Ca

ABSTRACTRetrieval of synaptic vesicles via endocytosis is essential for maintaining sustained synaptic transmission, especially for neurons that fire action potentials at high frequencies. However, how activity regulates synaptic vesicles recycling is largely unknown. Here we report that Na+ substantially accumulated in the mouse calyx of Held terminals during repetitive high-frequency spiking. Elevated presynaptic Na+ accelerated both slow and rapid forms of endocytosis and facilitated endocytosis overshoot but did not affect the readily releasable pool size, Ca2+ influx, or exocytosis. To examine whether this facilitation of endocytosis is related to the Na+-dependent vesicular content change, we dialyzed increasing concentrations of glutamate into the presynaptic cytosol or blocked the vesicular glutamate uptake with bafilomycin and found the rate of endocytosis was not affected by regulating the glutamate content in the presynaptic terminal. Endocytosis is critically dependent on intracellular Ca2+, and the activity of Na+/Ca2+ exchanger (NCX) may be altered when the Na+ gradient is changed. However, neither NCX blocker nor change of extracellular Na+ concentration affected the endocytosis rate. Moreover, two-photon Ca2+ imaging showed that presynaptic Na+ did not affect the action potential-evoked intracellular Ca2+ transient and decay. Therefore, we revealed a novel mechanism of cytosolic Na+ in accelerating vesicle endocytosis. During high-frequency synaptic transmission, when large amounts of synaptic vesicles are fused, Na+ accumulated in terminals, facilitated vesicle recycling and sustained reliable synaptic transmission.

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