Figure 1.

Main components of the model for ATP-induced activation of meningeal afferent (nerve fibers). (A) The experimental approach of meningeal spike recording by glass electrode from the local nerve (Aa) and the image of meninges with labeled mast cells (Ab). MMA—main meningeal artery. (B) Schematic presentation of the model neuroimmune synapse with a mast cell (“presynaptic cell”) as the source of the transmitter of ATP (or 5-HT) and meningeal nerve fiber (“postsynaptic cell”) consisting of several compartments with ATP-gated P2X3 receptors. (C) Changes in the membrane potential of the nerve fiber (spike generation) triggered by activation of the P2X3 receptor. (D) Ionic currents through several subtypes of sodium, potassium, and P2X3 receptor channels. (E) The graph showing the number of P2X3 receptors required to trigger a spike as a function of nerve fiber diameter. (F) The kinetics of P2X3 receptor-induced currents and the recovery time course from desensitization.