A novel type of calcium channel sensitive to omega-agatoxin-TK in cultured rat cerebral cortical neurons.
We characterized the electrophysiological properties of calcium channels in cultured rat cerebral cortical neurons using omega-agatoxin-TK (omega-Aga-TK) by a patch-clamp technique. Two types of slowly inactivating calcium channels sensitive to omega-Aga-TK were detected. The first type showed high sensitivity to omega-Aga-TK and low recovery from the omega-Aga-TK-induced blockade during washout, corresponding to the P-type channel. The second type showed low sensitivity to omega-Aga-TK and high recovery, resembling the Q-type channel, although it was distinct from the Q-type in terms of slower inactivation kinetics. We designate this channel as Q(L)-type (long-lasting Q channel). The omega-Aga-TK-sensitive calcium channels involved in the glutamatergic synaptic transmission were also divided into two types based on the sensitivity to omega-Aga-TK and reversibility of omega-Aga-TK-induced blockade. We conclude that the Q(L)-type is a novel type of channel, and that both P-type and Q(L)-type channels play a significant role in the cerebral cortical synaptic transmission.
Teramoto
T
T
Eisai Tsukuba Research Laboratories, Ibaraki, Japan.
Niidome
T
T
Kimura
M
M
Ohgoh
M
M
Nishizawa
Y
Y
Katayama
K
K
Mayumi
T
T
Sawada
K
K
D060848:Agatoxins; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D004594:Electrophysiology; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats / Q000196:embryology; D017208:Rats, Wistar; D013111:Spider Venoms / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000502:physiology
D060848:Agatoxins; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D013111:Spider Venoms; C083855:omega-agatoxin-Aa4b