Intracellular Ca(2+) oscillations induced by over-expressed Ca(V)3.1 T-type Ca(2+) channels in NG108-15 cells.

M. Chevalier, C. Mironneau, N. Macrez, J.F. Quignard
Cell Calcium. 2008-12-01; 44(6): 592-603
DOI: 10.1016/j.ceca.2008.04.003

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1. Cell Calcium. 2008 Dec;44(6):592-603. doi: 10.1016/j.ceca.2008.04.003. Epub 2008
Jun 20.

Intracellular Ca(2+) oscillations induced by over-expressed Ca(V)3.1 T-type
Ca(2+) channels in NG108-15 cells.

Chevalier M(1), Mironneau C, Macrez N, Quignard JF.

Author information:
(1)CNIC, CNRS UMR5228, Université de Bordeaux, Avenue des facultés, 33430
Talence, France.

T-type Ca(2+) channel family includes three subunits Ca(V)3.1, Ca(V)3.2 and
Ca(V)3.3 and have been shown to control burst firing and intracellular Ca(2+)
concentration ([Ca(2+)](i)) in neurons. Here, we investigated whether Ca(V)3.1
channels could generate a pacemaker current and contribute to cell excitability.
Ca(V)3.1 clones were over-expressed in the neuronal cell line NG108-15. Ca(V)3.1
channel expression induced repetitive action potentials, generating spontaneous
membrane potential oscillations (MPOs) and concomitant [Ca(2+)](i) oscillations.
These oscillations were inhibited by T-type channels antagonists and were present
only if the membrane potential was around -61mV. [Ca(2+)](i) oscillations were
critically dependent on Ca(2+) influx through Ca(V)3.1 channels and did not
involve Ca(2+) release from the endoplasmic reticulum. The waveform and frequency
of the MPOs are constrained by electrophysiological properties of the Ca(V)3.1
channels. The trigger of the oscillations was the Ca(V)3.1 window current. This
current induced continuous [Ca(2+)](i) increase at -60mV that depolarized the
cells and triggered MPOs. Shifting the Ca(V)3.1 window current potential range by
increasing the external Ca(2+) concentration resulted in a corresponding shift of
the MPOs threshold. The hyperpolarization-activated cation current (I(h)) was not
required to induce MPOs, but when expressed together with Ca(V)3.1 channels, it
broadened the membrane potential range over which MPOs were observed. Overall,
the data demonstrate that the Ca(V)3.1 window current is critical in triggering
intrinsic electrical and [Ca(2+)](i) oscillations.

DOI: 10.1016/j.ceca.2008.04.003
PMID: 18571720 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus