Ecto-ATPase activity in cerebellum: implication to the function of synaptic transmission.

The involvement of ATP in synaptic transmission was examined in synapses on granule cells of the rat cerebellum using ecto-ATPase activity. Reaction product was found in a majority but not all synapses between axodendritic, axoaxonic, and dendrodendritic appositions of granule cells and was associated with extracellular surface of both pre- and postsynaptic membranes. Specificity of the detection was justified by using diethyl pyrocarbonate, specific inhibitor of ecto-ATPase activity. These observations provide direct morphological evidence in support of the view that ATP participates in synaptic transmission and indicate functional heterogeneity of synapses in cerebellum.