High- and low-threshold calcium currents in neurons acutely isolated from rat sensorimotor cortex.
Neurons were isolated by papain treatment and trituration of the frontoparietal cortex of 14 to 28-day-old rats. Whole cell voltage clamp revealed a slowly inactivating high-threshold Ca2+ current, activated positive to -45 mV, and a transient low-threshold Ca2+ current, activated positive to -65 mV. The high-threshold current was more sensitive to block by Cd2+ and the low-threshold current was more sensitive to block by Ni2+. Replacement of Ca2+ by Ba2+ increased the high-threshold current and reduced the low-threshold current. The high-threshold current was enhanced by Bay K 8644 and reduced by nimodipine and omega-conotoxin. The low-threshold current was also reduced by nimodipine but was insensitive to Bay K 8644 and omega-conotoxin. The properties of the currents were consistent with different underlying Ca2+ channel types.
Sayer
R J
RJ
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195.
Schwindt
P C
PC
Crill
W E
WE
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008978:Mollusk Venoms / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009532:Nickel / Q000494:pharmacology; D009553:Nimodipine / Q000494:pharmacology; D010296:Parietal Lobe / Q000502:physiology; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D013003:Somatosensory Cortex / Q000502:physiology*; D020960:omega-Conotoxins
D008978:Mollusk Venoms; D010456:Peptides, Cyclic; D020960:omega-Conotoxins; D002104:Cadmium; C053423:Conus magus toxin; D001464:Barium; D009553:Nimodipine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009532:Nickel; D002118:Calcium