Subcellular localization of cyclic nucleotide phosphodiesterase in the caudate nucleus

The subcellular localization of cyclic nucleotide phosphodiesterase activity is described in the caudate nucleus and the neocortex of the cat and rat. Reaction product is visualized postsynaptically at asymmetrical axodendritic synapses by the statu nascendi precipitation of lead phosphate. The effect of varying substrate concentrations and incubation times to localize enzyme activity at cortical and caudate synapses in the two species is discussed. Demonstration of phosphodiesterase activity at postsynaptic sites adds further indirect evidence suggesting a role for cyclic nucleotides in synaptic transmission.