Stimulation of spontaneous transmitter release by the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, an activator of protein kinase C

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Colleges, School and Institutes


Treatment of frog neuromuscular preparations with the protein kinase C activator 12-O-tetradecanoylphorbol-13-acetate (TPA) (100 nM) resulted in a 40% rise in the frequency of miniature endplate potentials (MEPPs) (P less than 0.05). When these experiments were repeated on preparations bathed in saline containing 10 mM K+ (a procedure that raises MEPP frequency by approximately 10-fold due to the elevated level of [Ca2+]i), TPA caused a 70-75% increase in MEPP frequency (P less than 0.02), although the data did not differ significantly from those recorded in standard frog saline due to the variability between preparations. It is concluded that transmitter release mechanisms may be modulated by protein kinase C and that such modulation probably acts synergistically with [Ca2+]i.


Original languageEnglish
Pages (from-to)185-7
Number of pages3
JournalBrain Research
Issue number1
Publication statusPublished - 29 Apr 1985


  • Animals, In Vitro Techniques, Membrane Potentials, Motor Endplate, Neuromuscular Junction, Phorbols, Protein Kinase C, Protein Kinases, Rana pipiens, Synaptic Transmission, Tetradecanoylphorbol Acetate