Effects of phorbol ester on spontaneous transmitter release at frog neuromuscular junction.
Spontaneous transmitter release was studied at frog neuromuscular junctions exposed to the tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA), a specific activator of protein kinase C (PrkC). TPA at concentrations between 10(-7) and 10(-6) M induced a dose-dependent increase in miniature end-plate potential frequency. This frequency increase was enhanced by raising [Ca]o, diminished by lowering the temperature of the bath and virtually abolished in Ca2+ -free Ringer. The TPA effect was only poorly reversible after washing. TPA was ineffective in increasing spontaneous release of transmitter at phosphatidylcholine-pretreated neuromuscular junctions. It is suggested that PrkC might play a role in neuromuscular transmission processes.
Eusebi
F
F
Molinaro
M
M
Caratsch
C G
CG
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000187:drug effects / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism; D010704:Phorbols / Q000494:pharmacology*; D011894:Rana pipiens; D011896:Rana temporaria; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D018377:Neurotransmitter Agents; D010704:Phorbols; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium