A potent depressant action of adenine derivatives on cerebral cortical neurones.

Adenosine and several adenine nucleotides depress the excitability of cerebral cortical neurones, including identified Betz cells. Cyclic 3',5'-adenosine monophosphate was a less effective depressant than various other adenine nucleotides, including cyclic 2',3'-adenosine monophosphate. Adenine and inosine had only weak depressant activity. An initial excitant action of ATP was observed on several neurones. This was succeeded by a depressant effect when the application of ATP was terminated.