3,4-Diaminopyridine-evoked norepinephrine release and B-50 (GAP-43) phosphorylation
Huang, H.Y.; Tang, T.; Chen, X.F.
Zhongguo Yao Li Xue Bao 14(1): 35-38
1993
ISSN/ISBN: 0253-9756 PMID: 8503284 Document Number: 415454
3,4-Diaminopyridine (3,4-DAP 100 mu-mol cntdot L-1) evoked (3H)norepinephrine ((3H)NE) release in rat hippocampal slices preincubated with (3H)NE and superfused with medium with or without Ca-2+. Phorbolester 4-beta-phorbol 12, 13, dibutyrate (1 mu-mol cntdot L-1) enhanced and polymyxin B (100 mu-mol cntdot 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 Ca-2+ and completely inhibited by removal of extracellular Ca-2+ and completely inhibited by removal of extracellular Ca-2+. It was suggested that B-50 phosphorylation was not involved in 3,4-DAP-evoked (3H)NE release.