“Theophylline, an inhibitor of phosphodiesterase, caused axons to respond repetitively to stimulation, but this activity had a different pattern from that … and NaF. Imidazole, an activator of phosphodiesterase, impaired neuromuscular transmission and prevented the effects of dibutyryl cAMP and NaF. Adenosine , an inhibitor of protein … to dibutyryl cAMP, NaF ….”