Depression of the firing of rat cerebral cortical neurons by 2-azido analogues of adenine nucleotides.

Iontophoretically applied 2-azido photoaffinity analogues of adenosine 5'-triphosphate (ATP) and adenosine 5'-monophosphate (AMP) have been tested on rat cerebral cortical neurons. 2-Azido-AMP and 2-azido-ATP had a powerful depressant action on the spontaneous firing of cortical neurons. Both compounds were equipotent with AMP in terms of the maximum depression elicited by equivalent current applications but the rate of recovery was markedly slowed after application of the azido analogues. The adenosine antagonist 8-(p-sulphophenyl)theophylline prevented 2-azido-AMP and 2-azido-ATP from exerting their effects. The 2-azido analogues of adenosine may be useful ligands for further studies on central adenosine receptors.