Volatile Anesthetic Effects on Intracellular Ca2+ Dynamics Influence Synaptic Vesicle Exocytosis

Ca²⁺ influx through presynaptic voltage-gated Ca²⁺ channels (Caᵥ) is required for neurotransmitter release. Volatile anesthetic effects on synaptic transmission and neurotransmitter release are mediated by inhibition of presynaptic Ca²⁺ influx, but the detailed mechanisms by which anesthetics reduce presynaptic Ca²⁺ are not fully understood. Ligand-gated ion channels, including Naᵥ and Caᵥ, as well as targets regulating intracellular Ca²⁺ stores, are leading candidates for anesthetic effects on intracellular Ca²⁺.

Live-Cell Imaging of Endoplasmic Reticulum Specific Calcium

Rat hippocampal neurons (14 DIV) transfected with vGlut-pHluorin during electrical stimulation [50 action potentials at 50 Hz (open circle)].

Rat hippocampal neurons (14 DIV) transfected with ER-GCaMP during electrical stimulation [20 action potentials at 20 Hz (open circle)].

Fluorescence Traces of vGlut-pHluorin

 

Fluorescence traces of a single bouton from a neuron transfected with vGlut-pHluorin. w-Aga blocked P/Q-type mediated exoctytosis; 2 MAC isoflurane inhibited residual N-type mediated exocytosis. 

Fluorescence traces of a single bouton from a neuron transfected with vGlut-pHluorin. 𝜔-Aga blocked P/Q-type mediated exocytosis; isoflurane inhibited residual N-type Ca²⁺ channel- mediated exocytosis.

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