Inhibition of Ca-channels by diazepam compared with that by nicardipine in pheochromocytoma PC12 cells

Ken Nakazawa, Kazuhide Inoue, Mica Ohara-Imaizumi, Kannosuke Fujimori, Akira Takanaka

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The effects of diazepam on voltage-gated Ca channels were studied in PC12 pheochromocytoma cells using whole-cell voltage-clamp techniques. An inward current activated by a depolarizing voltage step to +10 mV from a holding potential of -60 mV in 10.8 mM Ba was larger than thatactivated in 10.8 mM Ca. The Ba current was completely blocked by a low concentration of Cd (30 μM) and was also sensitive to nicardipine (100 nM to 10 μM). Diazepam (1-100 μM) inhibited the Ba current in a concentration-dependent manner. Neither diazepam nor nicardipine affected the current-voltage relationship or the dependence on holding potentials of the Ba current. Both slightly accelerated the inactivation time course of the Ba current. When diazepam was applied to the cells in combination with nicardipine, the observed inhibition agreed with a value predicted assuming independent blockade by diazepam and by nicardipine. These results suggest that diazepam inhibits Ca channels in a manner similar to nicardipine, but that the binding sites for diazepam are different from those for nicardipine.

Original languageEnglish
Pages (from-to)44-50
Number of pages7
JournalBrain Research
Volume553
Issue number1
DOIs
Publication statusPublished - Jul 5 1991
Externally publishedYes

Fingerprint

Nicardipine
PC12 Cells
Pheochromocytoma
Diazepam
Patch-Clamp Techniques
Binding Sites

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

Cite this

Inhibition of Ca-channels by diazepam compared with that by nicardipine in pheochromocytoma PC12 cells. / Nakazawa, Ken; Inoue, Kazuhide; Ohara-Imaizumi, Mica; Fujimori, Kannosuke; Takanaka, Akira.

In: Brain Research, Vol. 553, No. 1, 05.07.1991, p. 44-50.

Research output: Contribution to journalArticle

Nakazawa, Ken ; Inoue, Kazuhide ; Ohara-Imaizumi, Mica ; Fujimori, Kannosuke ; Takanaka, Akira. / Inhibition of Ca-channels by diazepam compared with that by nicardipine in pheochromocytoma PC12 cells. In: Brain Research. 1991 ; Vol. 553, No. 1. pp. 44-50.
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