[3,4-Diaminopyridine-evoked norepinephrine release and B-50 (GAP-43) phosphorylation].
3,4-Diaminopyridine (3,4-DAP 100 mumol.L-1) evoked [3H]norepinephrine ([3H]NE) release in rat hippocampal slices preincubated with [3H]NE and superfused with medium with or without Ca2+. Phorbolester 4 beta-phorbol 12, 13, dibutyrate 1 mumol.L-1) enhanced and polymyxin B (100 mumol.L-1) inhibited the release of [3H]NE under both conditions. The neuron-specific protein B-50 is a major presynaptic substrate of protein kinase C and involved in exocytosis. Using in situ protein phosphorylation analyzed by SDS-PAGE and autoradiography, we observed that B-50 phosphorylation was significantly decreased by 3,4-DAP in the presence of extracellular Ca2+ and completely inhibited by removal of extracellular Ca2+. It was suggested that B-50 phosphorylation was not involved in 3,4-DAP-evoked [3H]NE release.
Shanghai Institute of Physiology, Chinese Academy of Sciences.
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Huang
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Chen
D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077770:Amifampridine; D000818:Animals; D019922:GAP-43 Protein; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate; D010766:Phosphorylation; D011112:Polymyxin B / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D015240:Phorbol 12,13-Dibutyrate; D015761:4-Aminopyridine; D011112:Polymyxin B; D000077770:Amifampridine; D009638:Norepinephrine