Up-regulation of L-type Ca2+ channel associated with the development of elevated K(+)-mediated survival of superior cervical ganglion cells in vitro.
We have previously shown that elevated K(+)-mediated neuronal survival correlates well with a sustained increase in cytoplasmic Ca2+ ([Ca2+]i) through the opening of L-type Ca2+ channels. Elevated K+ (40 mM), however, failed to support the survival of superior cervical ganglion (SCG) cells freshly isolated from newborn rats, while another depolarizing agent, veratridine, was able to do so, suggesting that elevated K(+)-mediated Ca2+ influx occurs in a stage-dependent manner. Indeed, sustained levels of [Ca2+]i in response to high K+ remained low (91 nM) in these neurons, but became elevated (238 nM) in SCG neurons which had been exposed to nerve growth factor (NGF) for 5-7 days and were capable of responding to elevated K+ by survival. Semiquantitative PCR measurements of L-type Ca2+ channel mRNA revealed that this transcript increased dramatically during incubation with NGF for 3 days and reached a plateau level at Day 5 (seven-fold per surface area or nine-fold per total volume compared to that at Day 1). These findings show that NGF-mediated up-regulation of the expression of L-type Ca2+ channel mRNA correlates with the development of elevated K(+)-mediated neuronal survival in vitro and suggest its involvement in coordinate strengthening of pre- and postganglionic synapses in rat SCG neurons.
Tanaka
S
S
Department of Natural Science, Saga Medical School, Japan.
Koike
T
T
D000818:Animals; D001483:Base Sequence; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D017931:DNA Primers; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011188:Potassium / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017783:Superior Cervical Ganglion / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation; D014701:Veratridine / Q000494:pharmacology
D015220:Calcium Channels; D017931:DNA Primers; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D014701:Veratridine; D011188:Potassium