P-type calcium channels in rat central and peripheral neurons.
The peptide toxin omega-Aga-IVA blocked P-type Ca2+ channel current in rat Purkinje neurons (KD approximately 2 nM) but had no effect on identified T-type, L-type, or N-type currents in a variety of central and peripheral neurons. omega-Aga-IVA blocked a substantial fraction of high threshold Ca2+ channel current in neurons from the hippocampal CA1 region (mean 26%), visual cortex (32%), spinal cord (45%), and dorsal root ganglia (23%), but less in hippocampal CA3 neurons (14%) and none in sympathetic neurons. In all cases, omega-Aga-IVA block could be reversed by a brief train of strong depolarizations. There was no overlap between current blocked by omega-Aga-IVA and the fractions blocked by dihydropyridines and omega-conotoxin GVIA, but not all current resistant to dihydropyridines and omega-conotoxin was blocked by omega-Aga-IVA. The results suggest that omega-Aga-IVA is highly selective for P-type channels and that many central neurons and some peripheral neurons possess substantial P-type current.
Mintz
I M
IM
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.
Adams
M E
ME
Bean
B P
BP
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology / Q000648:ultrastructure*; D002478:Cells, Cultured; D002490:Central Nervous System / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D004095:Dihydropyridines / Q000494:pharmacology; D004558:Electric Stimulation; D005727:Ganglia, Spinal / Q000166:cytology; D006624:Hippocampus / Q000166:cytology; D009474:Neurons / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure*; D010456:Peptides, Cyclic / Q000494:pharmacology; D010525:Peripheral Nerves / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D011690:Purkinje Fibers / Q000187:drug effects / Q000502:physiology; D051381:Rats; D013111:Spider Venoms / Q000494:pharmacology; D013116:Spinal Cord / Q000166:cytology; D009435:Synaptic Transmission / Q000502:physiology; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004095:Dihydropyridines; D010456:Peptides, Cyclic; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA