P2X receptor-mediated excitatory synaptic currents in somatosensory cortex.

Fast P2X receptor-mediated excitatory postsynaptic current (EPSC) was found in pyramidal neurones of layer V of somatosensory cortex in slices acutely isolated from the brain of 17- to 22-day-old rats. The EPSCs were elicited by field electrical stimulation in the layer VI at 0.1 Hz in the presence of picrotoxin. When the glutamatergic EPSC was blocked by glutamate receptors inhibitors NBQX and D-AP5, a residual EPSC (rEPSC) was recorded from 85% of neurones tested. This rEPSC was not affected by blockers of nicotinic (hexamethonium) and serotonin (Y25130) receptors; however, it was reversibly inhibited by P2X receptors antagonists (NF023, NF279, and PPADS). An application of ATP (20 microM), beta,gamma-methylene ATP (25 microM), and alpha,beta-methylene ATP (20 microM) to acutely isolated pyramidal neurones of layer V evoked inward currents (30 to 400 pA) in 75% of cells tested. We concluded that several subtypes of P2X purinoreceptors participate in synaptic transmission in neocortex.