Brain benzodiazepine levels following intravenous administration of [34]diazepam: relationship to the potentiation of purinergic depression of central nervous system neurons.

Levels of [3H]benzodiazepine were measured in rat cerebral cortex following intravenous injection of [3H]diazepam using a dose and time schedule reported to elicit a marked potentiation of the depressant effects of iontophoretically applied 5'-AMP to rat cerebral cortical neurons. The levels of [3H]benzodiazepine obtained strongly suggest (i) that blockade of adenosine uptake as a mechanism for this potentiation is not consistent with the potency of diazepam as an inhibitor of adenosine uptake in vitro, and (ii) that a potentiative interaction of adenosine and diazepam may reflect the binding of these compounds to benzodiazepine receptors.