240 Rapid calcium imaging at presynaptic terminals of the spiny lobster neuromuscular junction

1996 ◽  
Vol 25 ◽  
pp. S42
Author(s):  
Kiyoshi Ohnuma ◽  
Shunnichi Ogawa ◽  
Naoya Suzuki ◽  
Hiromasa Kijima ◽  
Akiko Miwa ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Calcium Imaging ◽  
Spiny Lobster ◽  
Presynaptic Terminals

scholarly journals Cooperative Ca2+ Removal from Presynaptic Terminals of the Spiny Lobster Neuromuscular Junction

1999 ◽  
Vol 76 (4) ◽  
pp. 1819-1834 ◽  
Author(s):  
Kiyoshi Ohnuma ◽  
Tomoki Kazawa ◽  
Shunichi Ogawa ◽  
Naoya Suzuki ◽  
Akiko Miwa ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Spiny Lobster ◽  
Presynaptic Terminals

Effect of a spider toxin (JSTX) on excitatory postsynaptic current at neuromuscular synapse of spiny lobster

1987 ◽  
Vol 58 (2) ◽  
pp. 319-326 ◽  
Author(s):  
A. Miwa ◽  
N. Kawai ◽  
M. Saito ◽  
H. Pan-Hou ◽  
M. Yoshioka
Keyword(s):  
Membrane Potential ◽  
Neuromuscular Junction ◽  
Time Constant ◽  
Spiny Lobster ◽  
Neuromuscular Synapse ◽  
Ionic Channel ◽  
Excitatory Postsynaptic Potential ◽  
Excitatory Postsynaptic Current ◽  
Steady Level ◽  
The Relationship

1. We studied the blocking properties of a spider (Nephila clavata) toxin (JSTX) purified from venom on the spiny lobster neuromuscular junction. 2. When a small amount of JSTX was applied to the neuromuscular junction, the excitatory postsynaptic potential (EPSP) was partially suppressed. The amplitude of EPSPs remained at a steady level for several hours during the washing of the preparation, showing that the action of JSTX is irreversible. 3. We recorded the excitatory postsynaptic current (EPSC) from synaptic site using a macro-patch electrode. The amplitude of EPSC increased linearly with hyperpolarization of the membrane potential in the presence and absence of JSTX. 4. The decay phase time constant of EPSC and spontaneous EPSC was decreased by hyperpolarizing the membrane potential both in the absence and in the presence of JSTX. The relationship between the decay time constant and the membrane potential was not modified by JSTX. 5. It is suggested that JSTX irreversibly blocks EPSC by acting on the site that is apart from the ionic channel of the glutamate receptor molecule.

scholarly journals Presynaptic coupling by electrical synapses coordinates a rhythmic behavior by synchronizing the activities of a neuron pair

2021 ◽  
Vol 118 (20) ◽  
pp. e2022599118
Author(s):  
Ukjin Choi ◽  
Han Wang ◽  
Mingxi Hu ◽  
Sungjin Kim ◽  
Derek Sieburth
Keyword(s):  
Motor Neurons ◽  
Calcium Imaging ◽  
Presynaptic Terminals ◽  
Electrical Synapses ◽  
Electrical Currents ◽  
Neuronal Populations ◽  
Junction Protein ◽  
Rhythmic Behavior ◽  
Ectopic Activation ◽  
And Behavior

Electrical synapses are specialized structures that mediate the flow of electrical currents between neurons and have well known roles in synchronizing the activities of neuronal populations, both by mediating the current transfer from more active to less active neurons and by shunting currents from active neurons to their less active neighbors. However, how these positive and negative functions of electrical synapses are coordinated to shape rhythmic synaptic outputs and behavior is not well understood. Here, using a combination of genetics, behavioral analysis, and live calcium imaging in Caenorhabditis elegans, we show that electrical synapses formed by the gap junction protein INX-1/innexin couple the presynaptic terminals of a pair of motor neurons (AVL and DVB) to synchronize their activation in response to a pacemaker signal. Live calcium imaging reveals that inx-1/innexin mutations lead to asynchronous activation of AVL and DVB, due, in part, to loss of AVL-mediated activation of DVB by the pacemaker. In addition, loss of inx-1 leads to the ectopic activation of DVB at inappropriate times during the cycle through the activation of the L-type voltage-gated calcium channel EGL-19. We propose that electrical synapses between AVL and DVB presynaptic terminals function to ensure the precise and robust execution of a specific step in a rhythmic behavior by both synchronizing the activities of presynaptic terminals in response to pacemaker signaling and by inhibiting their activation in between cycles when pacemaker signaling is low.

Facilitation of neurotransmitter release at the spiny lobster neuromuscular junction

2000 ◽  
Vol 37 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Shun-ichi Ogawa ◽  
Tomoyasu Takeuchi ◽  
Kiyoshi Ohnuma ◽  
Naoya Suzuki ◽  
Akiko Miwa ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Neurotransmitter Release ◽  
Spiny Lobster

scholarly journals Calcium-activated potassium conductance in presynaptic terminals at the crayfish neuromuscular junction.

1991 ◽  
Vol 98 (6) ◽  
pp. 1161-1179 ◽  
Author(s):  
S Sivaramakrishnan ◽  
G D Bittner ◽  
M S Brodwick
Keyword(s):  
Neuromuscular Junction ◽  
Potassium Conductance ◽  
Presynaptic Terminal ◽  
Constant Current ◽  
Delayed Rectifier ◽  
Presynaptic Terminals ◽  
Potassium Conductances ◽  
Constant Current Pulse ◽  
Calcium Activated Potassium Conductance ◽  
Tetraethylammonium Ions

Membrane potential changes that typically evoke transmitter release were studied by recording intracellularly from the excitor axon near presynaptic terminals of the crayfish opener neuromuscular junction. Depolarization of the presynaptic terminal with intracellular current pulses activated a conductance that caused a decrease in depolarization during the constant current pulse. This conductance was identified as a calcium-activated potassium conductance, gK(Ca), by its disappearance in a zero-calcium/EGTA medium and its block by cadmium, barium, tetraethylammonium ions, and charybdotoxin. In addition to gK(Ca), a delayed rectifier potassium conductance (gK) is present in or near the presynaptic terminal. Both these potassium conductances are involved in the repolarization of the membrane during a presynaptic action potential.

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