D-600 blocks open Ca2+ channels more profoundly than closed ones

The open channel blocking action of the Ca2+ antagonists, D-600 and Cd2+, was investigated in single neurons isolated by enzymatic treatment from dorsal root ganglia of frog. Using a 'concentration clamp' (jump) technique Ca2+ antagonists were applied to the preparation just before (less t...

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Bibliographic Details
Published inBrain research Vol. 417; no. 1; p. 143
Main Authors Oyama, Y, Hori, N, Tokutomi, N, Akaike, N
Format Journal Article
LanguageEnglish
Published Netherlands 04.08.1987
Subjects
Animals
Cadmium - pharmacology
Calcium - metabolism
Gallopamil - pharmacology
Ganglia, Spinal - drug effects
Ion Channels - drug effects
Membrane Potentials
Neurons, Afferent - drug effects
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Summary:The open channel blocking action of the Ca2+ antagonists, D-600 and Cd2+, was investigated in single neurons isolated by enzymatic treatment from dorsal root ganglia of frog. Using a 'concentration clamp' (jump) technique Ca2+ antagonists were applied to the preparation just before (less than 100 ms) or during a depolarizing step which induced the maximal peak amplitude of Ca2+ current (ICa). The inhibitory action of D-600 was more pronounced when applied during a depolarizing step than when applied just before a depolarizing step. In contrast, Cd2+ was equally inhibitory, whether applied before or during the depolarization. Thus, D-600 affects open channels more quickly or more profoundly than closed ones, while Cd2+ acts equally on both open and closed Ca2+ channels.
ISSN:0006-8993
DOI:10.1016/0006-8993(87)90189-2