Taylor D A, Stone T W
Experientia. 1978 Apr 15;34(4):481-2. doi: 10.1007/BF01935940.
At low doses, theophylline blocks the neuronal depressant effects of 5'-AMP, but not cyclic AMP. Higher doses (100 mg/kg) block cyclic AMP responses and reduce the effects of noradrenaline and GABA. It is concluded that cyclic AMP does not depress neurones via the adenosine receptor.