Figure 7. Ca²⁺ entry via Ca²⁺-permeable ionotropic receptors inhibits Cav3 currents.

(a) Effect of 10 µM ATP application on the Cav3.1 current recorded in a tsA-201 cell expressing the P2X4 receptor. The Cav3.1 current recorded just before (blue trace) and just after (red trace) the application of an ATP solution (black trace, P2X4 current). (b) Summary of ATP effect on the Cav3.1, the Cav3.2 and the Cav3.3 current recorded in tsA-201 cells expressing or not (pcDNA3) the P2X4 receptor in the presence or in the absence of 2 mM Ca²⁺ in the extracellular solution (n = 5–23 per bar). (c) Inactivation kinetics of the Cav3 currents in the absence and in the presence of ATP (2 mM Ca²⁺, n = 11–18 per bar). (d) Steady-state inactivation properties of the Cav3 currents the presence and in the absence of ATP (2 mM Ca²⁺, n = 10–17 per point). (e) Summary of the effect of NMDA, 5-HT3, TRPA1 and TRPV1 receptor activation on the Cav3 current amplitude recorded in the presence or in the absence of 2 mM Ca²⁺ in the extracellular saline (n = 5–30 per bar). In all these experiments the HP is −80 mV.

DOI: http://dx.doi.org/10.7554/eLife.22331.013

Figure 7—figure supplement 1. Effect of P2X4 activation on membrane density of Cav3.3 channels.

(a) Schematic representation of a Cav3.3 channel construct containing an extracellular HA tag (located in the IS5-pore loop) used to measure its membrane expression in tsA-201 cells. The cells were co-transfected with the Cav3.3 channel and either the P2X4 receptor or the pcDNA3 plasmid. (b) Quantification by ELISA/luminometry of the membrane expression levels of HA-tagged Cav3.3 channels after treatment with 10 µM ATP. The histogram represents relative light unit (RLU) normalized toward the values obtained in the control condition (P2X4 without ATP treatment).

DOI: http://dx.doi.org/10.7554/eLife.22331.014