Adenosine potentiation and antagonism may account for the diverse behavioral actions of Ro 5-4864.

The actions of the p-chloroderivative of diazepam, Ro 5-4864 on the spontaneous discharges of rat cerebral cortical neurons and its interactions with depressions evoked by adenosine and adenosine 5'-N-ethylcarboxamide (NECA) were observed. Iontophoretically applied Ro 5-4864 had variable actions on cortical neuronal activity, exciting some neurons and depressing others. During the period of applications. Ro 5-4864 antagonized the depressant effects of NECA, whilst having less of an action on adenosine depressions. Following Ro 5-4864 application adenosine, but not NECA, depressions were potentiated in amplitude and duration for periods of up to 20 min. It is suggested that Ro 5-4864 has both antagonistic and potentiative interactions with adenosine.