Fig. 1.

A schematic diagram of the cell types and possible sources of ATP release during pain. ATP is released from a variety of cells, including epithelial cells (keratinocytes), immune cells (mast cells, macrophages), glial cells (microglial, astrocyte, and satellite glial cells), and neurons. Pannexin and connexin channels are shown in the cell types where they have been found to play a role in pain. Similarly, P2X or P2Y receptors are displayed in sensory nerves, DRG, and spinal cord, where they can transmit acute and/or chronic pain signals