title: Protein kinase C modulates field-evoked transmitter release from cultured rat cerebellar granule cells via a dendrotoxin-sensitive K+ channel.
abstract: The role of protein kinase C (PKC) in the control of neurotransmitter release from cultured rat cerebellar granule cells was investigated. Release of preloaded [3H]-D-aspartate which is incorporated into synaptic vesicles in this preparation was evoked by electrical field stimulation or elevated KCl. PKC activation by phorbol esters resulted in a large facilitation of field-evoked Ca(2+)-dependent [3H]-D-aspartate release and a lesser enhancement of KCl-stimulated release. Inhibition of PKC by Ro 31-8220 or staurosporine virtually abolished field-evoked release but had no effect on KCl-evoked release. Field-evoked, but not KCl-evoked, synaptic vesicle exocytosis monitored by the fluorescent vesicle probe FM2-10 was inhibited by staurosporine. PKC was not directly modulating neurite Ca2+ channels coupled to release, as Ro 31-8220 did not inhibit these channels. Activation or inhibition of PKC modulated field-evoked plasma membrane depolarization, but had no effect on KCl-evoked depolarization, consistent with a regulation of Na+ or K+ channels activated by field stimulation. No modulation of field-evoked neurite Na+ influx was seen using phorbol esters. Phorbol ester-induced facilitation of field-evoked [3H]-D-aspartate release and neurite Ca2+ entry was non-additive with that produced by the specific K+ channel antagonist dendrotoxin-1, suggesting that PKC modulates transmitter release from field-stimulated cerebellar granule cells by inhibiting a dendrotoxin-1-sensitive K+ channel.
authors.affiliation: Department of Pharmacology and Neuroscience, Ninewells Medical School, University of Dundee, UK. mcousin@cmri.usyd.edu.au
authors.forename: M A
authors.initials: MA
authors.lastname: Cousin
authors.forename: M
authors.initials: M
authors.lastname: McLaughlin
authors.forename: D G
authors.initials: DG
authors.lastname: Nicholls
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001224:Aspartic Acid / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002531:Cerebellum / Q000737:chemistry / Q000166:cytology* / Q000201:enzymology; D004546:Elapid Venoms / Q000494:pharmacology*; D004558:Electric Stimulation; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000502:physiology; D005456:Fluorescent Dyes; D047908:Intracellular Signaling Peptides and Proteins; D018942:Macrolides; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D016501:Neurites / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D009498:Neurotoxins / Q000494:pharmacology*; D010703:Phorbol Esters / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000737:chemistry / Q000201:enzymology; D013744:Tetanus Toxin / Q000494:pharmacology; D014316:Tritium