Inhibition of the voltage-dependent calcium currents in isolated frog sensory neurons by GABA-related agonistic compounds

Toru Maruyama, Jan C. Behrends, Norio Akaike

Research output: Contribution to journalArticle

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Abstract

Effects of GABAA-, barbiturate- and benzodiazepine receptor agonists and GABAB agonist, baclofen, on voltage-dependent Ca2+ current (ICa) were studied in isolated frog sensory neurons after suppression of Na+ and K+ currents using single-electrode voltage-clamp. GABA, muscimol, taurine and pentobarbital (PB) dose-dependently induced a transient Cl- current (ICl), while baclofen and diazepam (DZP) did not elicit any currents. With GABAA agonists such as GABA, muscimol and taurine, ICa was suppressed transiently, and the maximum inhibition of ICa occurred within 1 min. The suppression of ICa by all GABAA agonists was neither voltage dependent nor attenuated in the presence of either bicuculline or picrotoxin. In addition, there was no correlation between GABA- and baclofen-induced suppressions of ICa. The results suggest that the inhibition of ICa by GABAA receptor agonists is not due to either GABAA or GABAB receptor activation at least. The inhibition of ICa by baclofen, PB and DZP was persistent. PB suppressed the amplitude of ICa and also facilitated the inactivation process, suggesting that PB behaves as a Ca channel blocker. However, the mechanisms of ICa suppression by baclofen and DZP are the subject for a future study. The potency order of the drugs in reducing ICa was muscimol > GABA = DZP > baclofen > PB > taurine.

Original languageEnglish
Pages (from-to)97-105
Number of pages9
JournalNeuroscience Research
Volume6
Issue number2
DOIs
Publication statusPublished - Jan 1 1988

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Baclofen
Sensory Receptor Cells
Anura
gamma-Aminobutyric Acid
Pentobarbital
Diazepam
GABA-A Receptor Agonists
Calcium
Muscimol
Taurine
GABA-A Receptors
Picrotoxin
Bicuculline
Electrodes
Pharmaceutical Preparations

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

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Inhibition of the voltage-dependent calcium currents in isolated frog sensory neurons by GABA-related agonistic compounds. / Maruyama, Toru; Behrends, Jan C.; Akaike, Norio.

In: Neuroscience Research, Vol. 6, No. 2, 01.01.1988, p. 97-105.

Research output: Contribution to journalArticle

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