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. Author manuscript; available in PMC: 2010 Apr 1.
Published in final edited form as: Brain Res Rev. 2008 Dec 31;60(1):84–89. doi: 10.1016/j.brainresrev.2008.12.021

Fig. 1.

Fig. 1

N-type and T-type calcium channels in the primary afferent signaling pathway. High voltage-activated N-type channels are highly localized to presynaptic terminals in laminae I and II of the dorsal horn. Action potentials carried along dorsal root ganglion cells (mainly C- and Aδ-afferents) trigger the opening of pre-synaptic N-type calcium channels which in turn initiate the release of nociceptive transmitters such as glutamate, substance P and CGRP onto spinal interneurons and projection neurons. Low voltage-activated T-type calcium channels are primarily localized more upstream in the pathway and are thought to be both involved in generating sensory potentials out near free nerve endings, as well as being present in DRG cell bodies where they likely contribute to the generation and frequency of action potentials. Modified from Hildebrand and Snutch, 2006; Schaible and Richter, 2004.