Inactivation of single Ca2+ channels in rat sensory neurons by extracellular Ca2+.

Academic Article


  • 1. Single Ca2+ channels conducting 20 mM Ba2+ from adult rat dorsal root ganglion cells were characterized using the two‐electrode patch‐clamp technique configuration. 2. Channels demonstrating specific characteristics of conductance, voltage dependence and dihydropyridine sensitivity were classified as high‐threshold or L‐type Ca2+ channels. 3. Mean single‐channel current in 20 mM Ba2+ did not show inactivation, but inactivation occurred when using Ca2+ as a permeating ion. 4. Stimulus protocols were delivered alternately in the cell‐attached and whole‐cell electrode, while recording single‐channel activity and total Ca2+ current simultaneously. 5. A mean single‐channel Ba2+ current from a stimulated patch did not show inactivation. However, stimulation of a physiological whole‐cell Ca2+ current induced a marked inactivation of mean single‐channel Ba2+ current. 6. Complete Ca2+ current block by the addition of 200 microM Cd2+ in the external solution removed single‐channel inactivation in patches stimulated through a whole‐cell electrode. © 1994 The Physiological Society
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    Author List

  • Galli A; Ferroni A; Bertollini L; Mazzanti M
  • Start Page

  • 15
  • End Page

  • 26
  • Volume

  • 477
  • Issue

  • 1