A P2X PURINOCEPTOR EXPRESSED BY A SUBSET OF SENSORY NEURONS

ATP is known to depolarize sensory neurons, and may play a role in noc iceptor activation when released from damaged tissue(1-10). Here we re port the molecular cloning and characterization of a new member of the P2X receptor family(3,11,12), P2X(3), expressed by these cells, The c hannel transcript was present in a subset of rat dorsal-root-ganglion sensory neurons, some of which express nociceptor-associated markers; it was absent in other tissues that were tested, including sympathetic , enteric and central nervous system neurons. Moreover, when expressed in Xenopus oocytes, the channel showed an ATP-dependent cation flux, P2X(3) is the only ligand-gated channel known to be expressed exclusiv ely by a subset of sensory neurons. The remarkable selectivity of expr ession of the channel coupled with its sensory neuron-like pharmacolog y suggests that this channel may transduce ATP-evoked nociceptor activ ation.