Calcium‐activated currents in cultured neurones from rat dorsal root ganglia

Kevin P.M. Currie, Roderick H. Scott

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Voltage‐activated Ca2+ currents and caffeine (1 to 10 mm) were used to increase intracellular Ca2+ in rat cultured dorsal root ganglia (DRG) neurones. Elevation of intracellular Ca2+ resulted in activation of inward currents which were attenuated by increasing the Ca2+ buffering capacity of cells by raising the concentration of EGTA in the patch solution to 10 mm. Low and high voltage‐activated Ca2+ currents gave rise to Cl tail currents in cells loaded with CsCl patch solution. Outward Ca2+ channel currents activated at very depolarized potentials (Vc + 60 mV to + 100 mV) also activated Cl tail currents, which were enhanced when extracellular Ca2+ was elevated from 2 mm to 4 mm. The Ca2+‐activated Cl tail currents were identified by estimation of tail current reversal potential by use of a double pulse protocol and by sensitivity to the Cl channel blocker 5‐nitro 2‐(3‐phenylpropylamino) benzoic acid (NPPB) applied at a concentration of 10 μm. Cells loaded with Cs acetate patch solution and bathed in medium containing 4 mm Ca2+ also had prolonged Ca2+‐dependent tail currents, however these smaller tail currents were insensitive to NPPB. Release of Ca2+ from intracellular stores by caffeine gave rise to sustained inward currents in cells loaded with Cs acetate. Both Ca2+‐activated tail currents and caffeine‐induced inward currents recorded from cells loaded with Cs acetate were attenuated by Tris based recording media, and had reversal potentials positive to 0 mV suggesting activity of Ca2+‐activated cation channels. Our data may reflect (a) different degrees of association between Ca2+‐activated channels with voltage‐gated Ca2+ channels, (b) distinct relationships between channels and intracellular Ca2+ stores and Ca2+ homeostatic mechanisms, (c) regulation of Ca2+‐activated channels by second messengers, and (d) varying channel sensitivity to Ca2+, in the cell body of DRG neurones. 1992 British Pharmacological Society

Original languageEnglish (US)
Pages (from-to)593-602
Number of pages10
JournalBritish Journal of Pharmacology
Issue number3
StatePublished - Jul 1992
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology


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