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P-type calcium channels in rat central and peripheral neurons.
I M Mintz, M E Adams, B P Bean
, 9, 85-95
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.