Functional characterization of calcium channels localized on the growth cones of cultured rat dorsal root ganglion cells.
Ca2+ channels on growth cones of cultured rat dorsal root ganglion (DRG) neurons were functionally characterized with an optical method using Fura-2. An increase in intracellular calcium concentration ([Ca2+](i)) of the growth cone was induced in response to electrical stimulation to the DRG cell body. The ([Ca2+](i))-increase was partly inhibited by either of omega - conotoxin GVIA (omega - CgTx, 3 microM) or omega - agatoxin IVA (omega - aga IVA, 300 nM) and completely blocked by both present at the same time, but was not affected by nicardipine (30 microM). The omega - CgTx - as well as omega - aga IVA - sensitive Ca2+ channels were immunologically localized on the growth cones using field emission scanning electron microscopy. It is concluded that the omega - CgTx - as well as omea - aga IVA - sensitive Ca2+ channels are involved in the ([Ca2+](i))-increase in the growth cones of the cultured DRG neurons, leading to glutamate release before synapse formation.
Soeda
Hiromitsu
H
Department of Autonomic Physiology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
Tatsumi
Hitoshi
H
Kozawa
Yukishige
Y
Mishima
Hiroyuki
H
Imai
Ken
K
Katayama
Yoshifumi
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004357:Drug Synergism; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D016257:Fura-2; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D020439:Growth Cones / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D051381:Rats; D014018:Tissue Distribution; D020867:omega-Agatoxin IVA / Q000494:pharmacology; D020866:omega-Conotoxin GVIA / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D005456:Fluorescent Dyes; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA; D002118:Calcium; D016257:Fura-2