Pharmacological Dissection of the Crosstalk between NaV and CaV Channels in GH3b6 Cells

Thanks to the crosstalk between Na+ and Ca2+ channels, Na+ and Ca2+ homeostasis interplay in so-called excitable cells enables the generation of action potential in response to electrical stimulation. Here, we investigated the impact of persistent activation of voltage-gated Na+ (Na-V) channels by neurotoxins, such as veratridine (VTD), on intracellular Ca2+ concentration ([Ca2+](i)) in a model of excitable cells, the rat pituitary GH3b6 cells, in order to identify the molecular actors involved in Na+-Ca2+ homeostasis crosstalk. By combining RT-qPCR, immunoblotting, immunocytochemistry, and patch-clamp techniques, we showed that GH3b6 cells predominantly express the Na(V)1.3 channel subtype, which likely endorses their voltage-activated Na+ currents. Notably, these Na+ currents were blocked by ICA-121431 and activated by the beta-scorpion toxin Tf2, two selective Na(V)1.3 channel ligands. Using Fura-2, we showed that VTD induced a [Ca2+](i) increase. This effect was suppressed by the selective Na-V channel blocker tetrodotoxin, as well by the selective L-type Ca-V channel (LTCC) blocker nifedipine. We also evidenced that crobenetine, a Na-V channel blocker, abolished VTD-induced [Ca2+](i) elevation, while it had no effects on LTCC. Altogether, our findings highlight a crosstalk between Na-V and LTCC in GH3b6 cells, providing a new insight into the mode of action of neurotoxins.

Automated summary

This study investigates the interaction between Na+ and Ca2+ channels in GH3b6 cells, revealing a crosstalk between Na-V and LTCC and providing new insights into the mode of action of neurotoxins.