adenosine-5--o-(3-thiotriphosphate) and Pain

Differential effects of ATP on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium currents in rat dorsal root ganglion neurons were studied using the whole-cell variation of path-clamp technique. Currents were evoked by step depolarizations to 0 mV from a holding potential of -80 mV. ATP suppressed TTX-S sodium currents while it increased TTX-R sodium currents. The effects were concentration-dependent and were reversible upon washout with ATP-free external solution. ATP-gamma-S, a hydrolysis-resistant ATP analog, also affected two types of sodium currents similarly to ATP, excluding the possibility that the effects were caused by the products of ATP hydrolysis, namely adenosine. ATP by modulating sodium currents may exert profound effects on the transmission of sensory information such as nociception.

Topics: Adenosine Triphosphate; Affinity Labels; Animals; Animals, Newborn; Dose-Response Relationship, Drug; Ganglia, Spinal; Membrane Potentials; Neurons, Afferent; Pain; Patch-Clamp Techniques; Rats; Receptors, Purinergic P1; Receptors, Purinergic P2; Sodium Channels; Synaptic Transmission; Tetrodotoxin