ATP mediates excitatory synaptic transmission in mammalian neurones.

Adenosine 5'-triphosphate (ATP, 0.1-100 microM), produced inward currents in patch-clamped coeliac neurones from guinea-pig when studied in either the whole cell configuration or in excised (outside-out) patches. The P2-purinoceptor antagonists suramin (80-230 microM) or reactive blue 2 (2-20 microM) depressed the ATP-induced currents but not those produced by acetylcholine. Excitatory post-synaptic currents (e.p.s.cs) were observed in cultured neurones. E.p.s.cs had similar current-voltage relationships to currents evoked by ATP in excised patches and were reduced by suramin or reactive blue 2 to a similar extent as ATP currents. The results suggest that ATP is the excitatory neurotransmitter in cultures of these neurones.