Antinociceptive effect of different types of calcium channel inhibitors and the distribution of various calcium channel alpha 1 subunits in the dorsal horn of spinal cord in mice.

To understand better which voltage-dependent calcium channels (VGCCs) are involved in nociceptive neurotransmission, we investigated the pharmacological properties and distribution of VGCCs in the mouse spinal cord. A behavioral assay revealed that intrathecal injections of omega-agatoxin TK, omega-agatoxin IVA, omega-conotoxin GVIA, and SNX-482, which block P/Q-, P/Q-, N-, and R-type calcium channels, respectively, produced analgesic effects, while an L-type channel blocker had no such effect. An electrophysiological study demonstrated the presence of various types of VGCCs within dorsal root ganglion (DRG) neurons.

Inhibitory effect of pranidipine on N-type voltage-dependent Ca2+ channels in mice.

We investigated the N-type voltage-dependent calcium channel blocking action of pranidipine, a novel dihydropyridine (DHP) derivative. Pranidipine significantly suppressed KCl-induced intracellular calcium changes ([Ca(2+)](i)) in a dose-dependent fashion in dorsal root ganglion neurons. A patch-clamp investigation revealed a dose-dependent blocking effect on N-type currents.