[3,4-Diaminopyridine-evoked norepinephrine release from hippocampal in the absence of extracellular calcium].
Slices of rat hippocampus, preincubated with [3H]norepinephrine ([3H]NE), were superfused and stimulated by addition of 3,4-diaminopyridine (3,4-DAP) for 10 min to the superfusion medium. 3,4-DAP-evoked [3H]NE release both in the absence and presence of extracellular Ca2+. 3,4-DAP-evoked Ca(2+)-independent release of [3H]NE was highly sensitive to sodium channel blocker, tetrodotoxin (TTX, 100% inhibition), suggesting that Na+ per se entered into nerve terminals but not depolarization of membrane followed by Ca2+ channel opening is necessary for 3,4-DAP-evoked Ca(2+)-independent release of [3H]NE. Phorbol ester PDB increased by 480% of control and polymyxin B (PMB) decreased 3,4-DAP-evoked [3H]NE release by 94% of control in the absence of extracellular Ca2+ indicating that the alterations of voltage-dependent Ca(2+)-currents into the cells are not involved in the mechanism of the modulation of 3,4-DAP-evoked [3H]NE release by protein kinase C.
Huang
H Y
HY
Shanghai Institute of Physiology, Chinese Academy of Sciences.
Dai
S P
SP
Xie
P G
PG
Xu
Y
Y
D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077770:Amifampridine; D000818:Animals; D002118:Calcium; D015220:Calcium Channels / Q000187:drug effects; D005110:Extracellular Space; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D015220:Calcium Channels; D015240:Phorbol 12,13-Dibutyrate; D015761:4-Aminopyridine; D011112:Polymyxin B; D000077770:Amifampridine; D002118:Calcium; D009638:Norepinephrine