Molecular Properties of Isolated Ca2+ Transport Systems from Nerve Terminals

Synaptic vesicles have important roles in the neural transmission at nerve terminals: the storage and the controlled exocytosis of neurotransmitters. At least two different factors are responsible for the concentration process: the vacuolar-type H(+)-ATPase (V-ATPase), establishing an electrochemical gradient of protons, and specific transport systems for transmitters. We will discuss our recent progress on the energy-transducing systems in synaptic vesicles: (1) structural aspects of V-ATPase; (2) energy coupling of transport of transmitters; (3) reconstitution of transporters; (4) effects of neurotoxins and neuron blocking agents; (5) function of synaptic-vesicle-like microvesicles from endocrine tissues.

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Roles of Na + –Ca 2+ exchange and of mitochondria in the regulation of presynaptic Ca 2+ and spontaneous glutamate release

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1999.0387 ◽

1999 ◽

Vol 354 (1381) ◽

pp. 357-364 ◽

Cited By ~ 33

Author(s):

Alessandra L. Scotti ◽

Jean–Yves Chatton ◽

Harald Reuter

Keyword(s):

Glutamate Release ◽

Additional Treatment ◽

Transport Systems ◽

Nerve Terminals ◽

Presynaptic Terminals ◽

Excitatory Postsynaptic Currents ◽

Postsynaptic Currents ◽

Mitochondrial Inhibitors ◽

Before And After ◽

Intracellular Ca

The release of neurotransmitter from presynaptic terminals depends on an increase in the intracellular Ca 2+ concentration ([Ca 2+ ] i ). In addition to the opening of presynaptic Ca 2+ channels during excitation, other Ca 2+ transport systems may be involved in changes in [Ca 2+ ] i .We have studied the regulation of[Ca 2+ ] i in nerve terminals of hippocampal cells in culture by the Na + –Ca 2+ exchanger and by mitochondria. In addition, we have measured changes in the frequency of spontaneous excitatory postsynaptic currents (sEPSC) before and after the inhibition of the exchanger and of mitochondrial metabolism. We found rather heterogeneous [Ca 2+ ] i responses of individual presynaptic terminals after inhibition of Na + –Ca 2+ exchange. The increase in [Ca 2+ ] i became more uniform and much larger after additional treatment of the cells with mitochondrial inhibitors. Correspondingly, sEPSC frequencies changed very little when only Na + –Ca 2+ exchange was inhibited, but increased dramatically after additional inhibition of mitochondria. Our results provide evidence for prominent roles of Na + Ca 2+ exchange and mitochondria in presynaptic Ca 2+ regulation and spontaneous glutamate release.

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Computer-Assisted Analysis of Multi-Color Confocal Microscopic Datasets: Automated Light Microscopic Discrimination of Synaptic Relationships

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163885 ◽

1996 ◽

Vol 54 ◽

pp. 284-285

Author(s):

M Wessendorf ◽

A Beuning ◽

D Cameron ◽

J Williams ◽

C Knox

Keyword(s):

Nerve Fibers ◽

Confocal Scanning Laser Microscopy ◽

Computer Assisted ◽

Nerve Terminals ◽

Neuronal Somata ◽

Scanning Laser Microscopy ◽

Confocal Scanning ◽

Entire Cell ◽

Confocal Scanning Laser ◽

Assisted Analysis

Multi-color confocal scanning-laser microscopy (CSLM) allows examination of the relationships between neuronal somata and the nerve fibers surrounding them at sub-micron resolution in x,y, and z. Given these properties, it should be possible to use multi-color CSLM to identify relationships that might be synapses and eliminate those that are clearly too distant to be synapses. In previous studies of this type, pairs of images (e.g., red and green images for tissue stained with rhodamine and fluorescein) have been merged and examined for nerve terminals that appose a stained cell (see, for instance, Mason et al.). The above method suffers from two disadvantages, though. First, although it is possible to recognize appositions in which the varicosity abuts the cell in the x or y axes, it is more difficult to recognize them if the apposition is oriented at all in the z-axis—e.g., if the varicosity lies above or below the neuron rather than next to it. Second, using this method to identify potential appositions over an entire cell is time-consuming and tedious.

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