title: P-type calcium channels in rat central and peripheral neurons.
abstract: 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.
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: I M
authors.initials: IM
authors.lastname: Mintz
authors.forename: M E
authors.initials: ME
authors.lastname: Adams
authors.forename: B P
authors.initials: BP
authors.lastname: Bean
mesh_terms: 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
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004095:Dihydropyridines; D010456:Peptides, Cyclic; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA