Which ion is required for release of neurotransmitter?

Which ion is required for release of neurotransmitter?

• A. Sodium
• B. Calcium
• C. Potassium
• D. Magnesium

Answer: (B)

The release of neurotransmitter depends on calcium ions entering the presynaptic terminal. When an action potential arrives, voltage-gated calcium channels open and Ca2+ rushes into the neuron. The rise in intracellular calcium binds to a sensor on the synaptic vesicles (such as synaptotagmin), triggering the SNARE complex to fuse the vesicle with the presynaptic membrane and causing exocytosis of neurotransmitter into the synaptic cleft. Sodium and potassium are mainly involved in generating and propagating the action potential, while magnesium has other roles, such as modulating receptor activity. The key trigger for release is calcium, so calcium is required.

The release of neurotransmitter depends on calcium ions entering the presynaptic terminal. When an action potential arrives, voltage-gated calcium channels open and Ca2+ rushes into the neuron. The rise in intracellular calcium binds to a sensor on the synaptic vesicles (such as synaptotagmin), triggering the SNARE complex to fuse the vesicle with the presynaptic membrane and causing exocytosis of neurotransmitter into the synaptic cleft. Sodium and potassium are mainly involved in generating and propagating the action potential, while magnesium has other roles, such as modulating receptor activity. The key trigger for release is calcium, so calcium is required.