Contributions of multiple calcium channel types to GABAergic transmission in rat cultured hippocampal neurons.
Effects of Ca2+ channel blockers on GABAergic transmission were examined with rat cultured hippocampal neurons. The GABAergic synaptic currents (IPSCs) evoked by electrical stimulation of single presynaptic neurons were recorded from voltage-clamped postsynaptic neurons. The amplitude of IPSCs was not changed by 10 microM nifedipine (L-type Ca2+ channel blocker), but was decreased irreversibly to 37% of control by 1 microM omega-conotoxin GVIA (N-type blocker, CgTX), to 67% by 0.1 microM omega-agatoxin IVA (P-type blocker, AGTX), and to 1% by both toxins. From these data and the Ca(2+)-dependence of IPSCs, the contributions of CgTX-sensitive and AGTX-sensitive Ca2+ channels to the transmission were estimated at 59% and 36%, respectively.
Ohno-Shosaku
T
T
Department of Physiology, Faculty of Medicine, Kanazawa University, Ishikawa, Japan.
Hirata
K
K
Sawada
S
S
Yamamoto
C
C
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004558:Electric Stimulation; D004594:Electrophysiology; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000502:physiology; D051381:Rats; D013111:Spider Venoms / Q000494:pharmacology; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D005680:gamma-Aminobutyric Acid; D020866:omega-Conotoxin GVIA; D009543:Nifedipine