Physiol. Res. 49: 475-479, 2000

RAPID COMMUNICATION

Cyclic AMP Synchronizes Evoked Quantal Release at Frog Neuromuscular Junctions

E. Bukcharaeva1,2, D. Samigullin2, E.E. Nikolsky1,2, F. Vyskočil3

1Kazan Medical University, Kazan, Russia, 2Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, 3Institute of Physiology, Academy of Sciences of the Czech Republic, and Department of Animal Physiology and Developmental Biology, Charles University, Prague, Czech Republic

Received May 4, 2000
Accepted June 15, 2000


Summary
At frog neuromuscular junction, noradrenaline (NA) shortens the release period for evoked quantal release acting on a b 1 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 1x10-6 mol/l db-cAMP and 1x10-6 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.


Key words
Acetylcholine · Frog muscle · cAMP · Quantal release

Reprint requests
F. Vyskočil, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4, Czech Republic. E-mail: vyskocil@biomed.cas.cz


© 2000 by the Institute of Physiology, Czech Academy of Sciences