The effect of N6-2'-O dibutyryl 3',5' cyclic adenosine monophosphate, imidazole and aminophylline on ganglionic transmission in the superior cervical ganglion of the cat.

1. Dibutyryl cyclic AMP, injected towards the superior cervical ganglion of the cat, produced no consistent responses.2. Imidazole, injected towards the ganglion, regularly produced facilitation, both during intermittent and continuous preganglionic stimulation. This effect was dose-dependent and lasted 2-10 minutes.3. Aminophylline, injected towards the ganglion, regularly produced depression of ganglionic transmission, both during intermittent and continuous preganglionic stimulation. This effect was also dose-dependent and lasted 1-4 minutes. Papaverine produced the same type of response as aminophylline.4. Imidazole potentiated the ganglionic response to 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), while aminophylline depressed it.5. The results of the present experiments are consistent with the view that cyclic AMP may have a mediating role in the process of ganglionic transmission.