Characterisation of the L- and N-type calcium channels in differentiated SH-SY5Y neuroblastoma cells: calcium imaging and single channel recording.
We have used single cell imaging of [Ca2+]i and single channel cell-attached patch clamp recording to characterise the Ca2+ channels present on the plasma membrane of retinoic acid-differentiated human neuroblastoma (SH-SY5Y) cells. Exposure to raised K+ (45 or 60 mM) for 1 min resulted in a transient rise in [Ca2+]i which was abolished by cadmium (100 microM). The amplitude of the evoked rise varied from cell to cell. Both omega-Conus toxin (500 nM) and nifedipine (10 microM) reduced, but did not abolish, the rise in [Ca2+]i whereas Bay K 8644 (3 microM) potentiated it. In single channel records both L- and N-type Ca2+ channel openings were observed during membrane depolarisations from a holding potential of -90 mV. L-type channel openings (unitary conductance 22.5 pS) were prolonged by S(+)-PN 202-791 (500 nM) and could still be evoked from a depolarised holding potential (-40 mV). N-type channel openings (unitary conductance 12.5 pS) were unaffected by the dihydropyridine agonist but were inactivated at a holding potential of -40 mV. These results indicate that, in contrast to previous observations using whole cell recording, retinoic acid-differentiated SH-SY5Y cells express both L- and N-type Ca2+ channels.
Morton
A J
AJ
Department of Pharmacology, University of Cambridge, U.K.
Hammond
C
C
Mason
W T
WT
Henderson
G
G
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D002104:Cadmium / Q000494:pharmacology; D019256:Cadmium Chloride; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D016257:Fura-2; D006801:Humans; D007700:Kinetics; D008856:Microscopy, Fluorescence; D009447:Neuroblastoma; D009539:Nicotinic Acids / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D010069:Oxadiazoles; D010456:Peptides, Cyclic / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology; D020960:omega-Conotoxins
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002712:Chlorides; D009539:Nicotinic Acids; D010069:Oxadiazoles; D010456:Peptides, Cyclic; D020960:omega-Conotoxins; D002104:Cadmium; C049834:PN 202-791; C053423:Conus magus toxin; D014212:Tretinoin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine; D019256:Cadmium Chloride; D011188:Potassium; D002118:Calcium; D016257:Fura-2