External Ca(2+)-independent norepinephrine release from hippocampal slices and modulation by protein kinase C activation.
4 beta-Phorbol 12,13-dibutyrate (PDB) enhanced [3H] norepinephrine ([3H]NE) release from rat hippocampal slices evoked by 3,4-diaminopyridine (3,4-DAP, 100-400 mumol.L-1), veratridine (1-7 mumol.L-1) or ouabain (100-200 mumol.L-1), but had no effect on those evoked by monensin (0.01-10 mumol.L-1) in the absence of extracellular Ca2+. Tetrodotoxin (TTX, 0.3 mumol.L-1) blocked [3H]NE release evoked by 3,4-DAP, veratridine, or ouabain, but failed to affect that evoked by monensin. Tetraacetoxy methyl ester of 1-2-bis-(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM), Ca2+ chelator, inhibited the [3H]NE release evoked by these substances, but did not inhibit the enhancement of the evoked NE release by PDB. The findings suggest that under external Ca(2+)-free conditions protein kinase C activation enhances [3H]NE release evoked by the membrane depolarizing agents, but does not affect that evoked by Na(+)-induced internal Ca2+ release.
Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai.
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Huang
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Xie
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Huang
D015761:4-Aminopyridine / Q000031:analogs & derivatives / Q000494:pharmacology; D000077770:Amifampridine; D000818:Animals; D002118:Calcium; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D008985:Monensin / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D015221:Potassium Channels; D011493:Protein Kinase C / Q000502:physiology*; D051381:Rats; D014701:Veratridine / Q000494:pharmacology
D015221:Potassium Channels; D015240:Phorbol 12,13-Dibutyrate; D010042:Ouabain; D014701:Veratridine; D008985:Monensin; D015761:4-Aminopyridine; D011493:Protein Kinase C; D000077770:Amifampridine; D002118:Calcium; D009638:Norepinephrine