title: Protein kinase C modulates the release of [3H]5-hydroxytryptamine in the spinal cord of the rat: the role of L-type voltage-dependent calcium channels.
abstract: The present studies examined the relationship between protein kinase C (PKC) and L-type voltage-dependent calcium channels in modulating the release of neurotransmitter from K(+)-depolarized rat spinal cord synaptosomes. Activators of PKC, such as phorbol 12-myristate 13-acetate (PMA), mezerein and oleoyl acetylglycerol produced a concentration-dependent potentiation of K(+)-induced release of [3H]5-hydroxytryptamine ([3H]5-HT). Enhanced release was dependent on the concentration of both Ca2+ and K+ in the superfusion medium. Calcium-independent release of [3H]5-HT or release induced by the Ca2+ ionophore were unaffected by PKC activators. Calcium-dependent release of [3H]5-HT, evoked by K+, was enhanced under similar conditions by the L-type Ca2+ channel agonists Bay K 8644 and (+)-SDZ 202-791. Nimodipine, an L-type Ca2+ channel antagonist, while having no independent effect on K(+)-induced release of [3H]5-HT, abolished the potentiative effects of Bay K 8644 and PMA. Similarly, the PKC inhibitors, polymyxin B and staurosporine, blocked effects of both PMA and Bay K 8644 on K(+)-stimulated release of [3H]5-HT. Neither PMA nor Bay K 8644 altered the uptake of [3H]5-HT. These results suggest that PKC-dependent mechanisms utilize calcium influx, via the L-type calcium channel, to modulate release of neurotransmitter and indicate a possible functional link between PKC and L-type voltage-dependent calcium channels in the spinal cord.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009568:Nitrendipine / Q000378:metabolism; D010456:Peptides, Cyclic / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*; D019311:Staurosporine; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020960:omega-Conotoxins
chemical_list: D000470:Alkaloids; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D009419:Nerve Tissue Proteins; D010456:Peptides, Cyclic; D020960:omega-Conotoxins; C053423:Conus magus toxin; D012701:Serotonin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009568:Nitrendipine; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium