The effects of changing intracellular Ca2+ buffering on the excitability of cultured dorsal root ganglion neurones.
The whole cell patch clamp technique was used to study the effects of changes in [Ca2+]i on the excitability of cultured dorsal root ganglion (DRG) neurones. Increases in [Ca2+]i caused membrane depolarization, altered the characteristics of evoked action potentials and activated potassium, chloride and non-selective cation conductances. Mobilization of Ca2+ from intracellular stores with caffeine (1 mM) or ryanodine (10 microM) or photorelease of Ca2+ from DM-nitrophen gave rise to depolarizations suggesting a dominant inward current under our recording conditions of low [Ca2+]i buffering capacity. The actions of [Ca2+]i could be partially reversed by intracellular flash photolysis of diazo-2 but not by diazo-3. The electrophysiological properties of some DRG neurones were not influenced by changes in [Ca2+]i and we suggest that this is because in this heterogeneous culture some neurones do not express Ca2+-activated ion channels.
Ayar
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A
Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Scotland, UK.
Storer
C
C
Tatham
E L
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Scott
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RH
D000085:Acetates / Q000494:pharmacology; D000818:Animals; D002021:Buffers; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D003979:Diazonium Compounds; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D005029:Ethylenediamines / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010642:Phenoxyacetates; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010777:Photochemistry; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology
D000085:Acetates; D002021:Buffers; D002614:Chelating Agents; D003979:Diazonium Compounds; D005029:Ethylenediamines; D010642:Phenoxyacetates; D010726:Phosphodiesterase Inhibitors; C063685:diazo-2; D012433:Ryanodine; C057014:DM-nitrophen; D002110:Caffeine; D004533:Egtazic Acid; D002118:Calcium