Marco Canepari

3 juillet 2015

Team "Neuron Imaging & Calcium Channels", Laboratoire interdisciplinaire de Physique (LIPhy), Equipe MOTIV, UMR 5588, CNRS-UJF, St. Martin-d’Hères (Grenoble)

The physiological synergistic activation of dendritic voltage-gated calcium channels

invité par Ivo Vanzetta

The physiological synergistic activation of dendritic voltage-gated calcium channels

Nadia Jaafari & Marco Canepari

Laboratoire Interdisciplinare de Physique (CNRS-UJF UMR 5588), France and Laboratories of Excellence, Ion Channel Science and Therapeutics

At pyramidal neurons, action potentials generated in the axon hillock back-propagate into the dendrites activating different types of voltage-gated Ca2+ channels (VGCCs). The consequent Ca2+ signal represents a precise code for the dendritic sites where the cell receives synaptic inputs and plays itself a role in the propagation of electrical signals within the dendrites. Using a recently developed optical technique (Jaafari et al. 2014) we investigated in detail the activation of dendritic VGCCs during physiological action potentials. All types of high-voltage activated (HVA) VGCCs (L-type, N-type and P/Q type) contribute to the kinetics of action potentials, in particular by activating K+ channels. The longer lasting action potential prolongs the duration of activation of low-voltage activated Ca2+ channels (T-type). The result is a compensation of the loss of the Ca2+ signal component mediated by LVA VGCCs with the larger component mediated by LVA VGCCs. Thus, functional coupling of VGCCs underlies the high-fidelity of fast dendritic Ca2+ signals during individual action potentials which occur in the majority of the dendritic field.

Jaafari N, De Waard M, Canepari M (2014) Imaging Fast Calcium Currents beyond the Limitations of Electrode Techniques. Biophys J 107 : 1280-1288.

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