A selective inhibitor of cAMP-specific phosphodiesterase, Ro 20-1724, has no effect on the quantal release of acetylcholine from the mouse phrenic nerve.
The indirect twitch response of the mouse isolated phrenic nerve-diaphragm preparation, partially paralysed by tubocurarine, was restored only by about 10% by Ro 20-1724 at 2 to 280 microM. The solvent vehicle, dimethylsulphoxide, also showed the same effect to a similar extent. Intracellular recordings with glass microelectrodes revealed that Ro 20-1724 (40 microM) affected neither the resting membrane potential, the amplitude and frequency of miniature endplate potentials nor the amplitude of nerve-impulse evoked endplate potentials recorded in curarized preparations. The result indicates that Ro 20-1724 at a concentration four times the IC50 of phosphodiesterase inhibition has no effect on the quantal release of acetylcholine from a mammalian motor nerve and suggests that cAMP has no modulatory effect on the transmitter release.
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology*; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D005260:Female; D007093:Imidazoles / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009045:Motor Endplate / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D010791:Phrenic Nerve / Q000187:drug effects / Q000378:metabolism*; D012132:Respiratory Muscles / Q000187:drug effects; D014403:Tubocurarine / Q000494:pharmacology
D007093:Imidazoles; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000109:Acetylcholine; D014403:Tubocurarine