title: P-type calcium channels in the somata and dendrites of adult cerebellar Purkinje cells.
abstract: The pharmacological and single-channel properties of Ca2+ channels were studied in the somata and dendrites of adult cerebellar Purkinje cells. The Ca2+ channels were exclusively of the high threshold type: low threshold Ca2+ channels were not found. These high threshold channels were not blocked by omega-conotoxin GVIA and were inhibited rather than activated by BAY K 8644. They were therefore pharmacologically distinct from high threshold N- and L-type channels. Funnel web spider toxin was an effective blocker. The channels opened to conductance levels of 9, 14, and 19 pS (in 110 mM Ba2+). These slope conductances were in the range of those reported for N- and L-type channels. Our results are in agreement with previous reports suggesting that Ca2+ channels in Purkinje cells can be classified as P-type channels according to their pharmacology. The results also suggest that distinctions among Ca2+ channel types based on the single-channel conductance are not definitive.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000502:physiology*; D003712:Dendrites / Q000502:physiology*; D004095:Dihydropyridines / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008564:Membrane Potentials; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D004095:Dihydropyridines; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C038806:1,4-dihydropyridine