Cyclic AMP synchronizes evoked quantal release at frog neuromuscular junctions.
At frog neuromuscular junction, noradrenaline (NA) shortens the release period for evoked quantal release acting on a beta1 receptor. To test the hypothesis that this action of NA is mediated by cAMP, we measured the latencies of focally recorded uni-quantal endplate currents (EPCs) after application of dibutyryl-cAMP (db-cAMP) and adenylyl cyclase activator, forskolin. The interval between the time when responses with minimal delay appeared and the point at which 90% of all latencies had occurred (P90 parameter) was shortened in the presence of both 1 x 10(-6) mol/l db-cAMP and 1 x 10(-6) mol/l forskolin by about 30%. The cAMP-induced shortening is equal to that found after application of NA and effects of both drugs are not additive.
Bukcharaeva
E
E
Kazan Medical University, Russia.
Samigullin
D
D
Nikolsky
E E
EE
Vyskocil
F
F
D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology*; D004594:Electrophysiology; D009469:Neuromuscular Junction / Q000502:physiology*; D011895:Rana ridibunda; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
D000242:Cyclic AMP; D000109:Acetylcholine