Pain is generated by activation of specific dorsal root ganglion (DRG) neurons termed the nociceptive neurons. The nociceptive DRG neurons express 3 categories of ionic channels a. Channels gated by pain stimuli, b. Channels responsible for the transmission of information from sensory receptors to the spinal cord, c. Channels resposible for the release of neurotransmitters in the spinal cord. There is evidency that kinetic properties, molecular structure and functional significance of the ionic channels expressed in nociceptive DRG neurons are different compared to the other types of DRG neurons. The ionic channels are strictly controlled by receptors for neurotransmitters expressed in the plasma membrane of nociceptive DRG neurons.