THE MECHANISM OF ATP-INDUCED LONG-TERM POTENTIATION INVOLVES EXTRACELLULAR PHOSPHORYLATION OF MEMBRANE-PROTEINS IN GUINEA-PIG HIPPOCAMPAL CA1 NEURONS

The mechanism of ATP-induced long-term potentiation was studied pharma cologically using guinea-pig hippocampal slices. Application of 1-10 m u M ATP for 10 min transiently depressed and then slowly augmented the synaptic transmission in CA1 neurons leading to long-term potentiatio n (LTP). This ATP-induced LTP was blocked by the addition of K-252b, a n ecto-protein kinase inhibitor, but was enhanced by the addition of R K682, an ecto-phosphatase inhibitor, both of which do not permeate the cell membrane. These results suggest that ATP applied to the perfusat e provides enough substrate for ecto-protein kinase to induce LTP thro ugh phosphorylation of extracellular domains of membrane proteins in C A1 neurons.