Distribution of nifedipine- and omega-conotoxin GVIA-sensitive Ca2+ channels in cultured rat neocortical neurons.
L- and N-type voltage-dependent calcium channels are widely distributed in neurons of the CNS. To investigate their subcellular distributions on CNS neurons, intracellular calcium concentration ([Ca2+]i) increase in response to high potassium ([K+]) solution was detected in primary cultured rat neocortical neurons using the calcium indicator dye Oregon Green with a confocal laser scanning microscope. Extracellular application of 90 mM [K+] solution induced fluorescence increase in a manner dependent on extracellular [Ca2+]. The increase was partially blocked by 10 microM nifedipine, and the reduction was higher in cell bodies compared to dendritic processes. In contrast, omega-conotoxin GVIA reduced the 90 mM [K+] induced fluorescence increase more in the dendritic processes. The results demonstrated the heterogeneous distribution of nifedipine- and omega-conotoxin GVIA-sensitive calcium channels, which may suggest a functional difference in nifedipine- and omega-conotoxin GVIA-sensitive channels in cultured neocortical neurons.
Wang
G
G
Department of Physiology II, Faculty of Medicine, Kagoshima University, Japan.
Hashiguchi
T
T
Sakamoto
Y
Y
Takigawa
M
M
Kameyama
M
M
D000465:Algorithms; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects*; D020864:Calcium Channels, N-Type; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D019579:Neocortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D020866:omega-Conotoxin GVIA
D002118:Calcium; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020864:Calcium Channels, N-Type; D005456:Fluorescent Dyes; D009543:Nifedipine; D010455:Peptides; D011188:Potassium; D020866:omega-Conotoxin GVIA