Mechanism of potentiation by diazepam of adenosine response.

Diazepam (3 microM) potentiates the adenosine-induced relaxation of caecum. Other benzodiazepine receptor ligands, such as inosine and hypoxanthine, failed to modify adenosine responses. Diazepam failed to further modify the dose-response curve to adenosine obtained in the presence of dipyridamole, and uptake inhibitor. Diazepam and dipyridamole did not affect the responses to 2-chloroadenosine. The relaxant effect of adenosine was not blocked by Ro 15-1788, a benzodiazepine receptor antagonist. These observations indicated that diazepam potentiated adenosine response by inhibiting the uptake of purine nucleotide and, that the benzodiazepine receptor is not purinergic in nature in the rat caecum.