Pharmacological dissection of high-voltage-activated Ca2+ current types in acutely dissociated rat supraoptic magnocellular neurons

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Abstract

1. We used pharmacological blockers and whole cell voltage-clamp recordings from acutely dissociated magnocellular neurons from the rat supraoptic nucleus to test for the presence of L-, N-, P-, Q-, and R-type calcium currents. 2. We found clear evidence for L-type (dihydropyridine sensitive), N-type (blocked by ω-conotoxin GVIA), and P-type (blocked by ω- agatoxin IVA) currents. Nifedipine blocked 28 ± 2% (mean ± SE) of the current, ω-conotoxin GVIA blocked 26 ± 4%, and ω-agatoxin IVA (25-30 nM) blocked 17 ± 4%. In addition, ω-conotoxin MVIIC blocked about half (54 ± 2%) of the current remaining after L-, N-, and P-type currents were blocked, suggesting the presence of Q-type currents. 3. About 20% of the whole cell current was unblocked by the combination of all four blockers, suggesting the presence of a fifth current type. This residual current inactivated slowly at -10 mV.

Original languageEnglish (US)
Pages (from-to)977-983
Number of pages7
JournalJournal of neurophysiology
Volume76
Issue number2
DOIs
StatePublished - Jan 1 1996

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Conotoxins
Agatoxins
Dissection
Pharmacology
Neurons
Supraoptic Nucleus
Nifedipine
Calcium

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Physiology

Cite this

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title = "Pharmacological dissection of high-voltage-activated Ca2+ current types in acutely dissociated rat supraoptic magnocellular neurons",
abstract = "1. We used pharmacological blockers and whole cell voltage-clamp recordings from acutely dissociated magnocellular neurons from the rat supraoptic nucleus to test for the presence of L-, N-, P-, Q-, and R-type calcium currents. 2. We found clear evidence for L-type (dihydropyridine sensitive), N-type (blocked by ω-conotoxin GVIA), and P-type (blocked by ω- agatoxin IVA) currents. Nifedipine blocked 28 ± 2{\%} (mean ± SE) of the current, ω-conotoxin GVIA blocked 26 ± 4{\%}, and ω-agatoxin IVA (25-30 nM) blocked 17 ± 4{\%}. In addition, ω-conotoxin MVIIC blocked about half (54 ± 2{\%}) of the current remaining after L-, N-, and P-type currents were blocked, suggesting the presence of Q-type currents. 3. About 20{\%} of the whole cell current was unblocked by the combination of all four blockers, suggesting the presence of a fifth current type. This residual current inactivated slowly at -10 mV.",
author = "Robert Foehring and William Armstrong",
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N2 - 1. We used pharmacological blockers and whole cell voltage-clamp recordings from acutely dissociated magnocellular neurons from the rat supraoptic nucleus to test for the presence of L-, N-, P-, Q-, and R-type calcium currents. 2. We found clear evidence for L-type (dihydropyridine sensitive), N-type (blocked by ω-conotoxin GVIA), and P-type (blocked by ω- agatoxin IVA) currents. Nifedipine blocked 28 ± 2% (mean ± SE) of the current, ω-conotoxin GVIA blocked 26 ± 4%, and ω-agatoxin IVA (25-30 nM) blocked 17 ± 4%. In addition, ω-conotoxin MVIIC blocked about half (54 ± 2%) of the current remaining after L-, N-, and P-type currents were blocked, suggesting the presence of Q-type currents. 3. About 20% of the whole cell current was unblocked by the combination of all four blockers, suggesting the presence of a fifth current type. This residual current inactivated slowly at -10 mV.

AB - 1. We used pharmacological blockers and whole cell voltage-clamp recordings from acutely dissociated magnocellular neurons from the rat supraoptic nucleus to test for the presence of L-, N-, P-, Q-, and R-type calcium currents. 2. We found clear evidence for L-type (dihydropyridine sensitive), N-type (blocked by ω-conotoxin GVIA), and P-type (blocked by ω- agatoxin IVA) currents. Nifedipine blocked 28 ± 2% (mean ± SE) of the current, ω-conotoxin GVIA blocked 26 ± 4%, and ω-agatoxin IVA (25-30 nM) blocked 17 ± 4%. In addition, ω-conotoxin MVIIC blocked about half (54 ± 2%) of the current remaining after L-, N-, and P-type currents were blocked, suggesting the presence of Q-type currents. 3. About 20% of the whole cell current was unblocked by the combination of all four blockers, suggesting the presence of a fifth current type. This residual current inactivated slowly at -10 mV.

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