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. 1989 Mar;86(5):1736–1740. doi: 10.1073/pnas.86.5.1736

Calcium channel block by cadmium in chicken sensory neurons.

D Swandulla 1, C M Armstrong 1
PMCID: PMC286776  PMID: 2537985

Abstract

Cadmium block of calcium channels was studied in chicken dorsal root ganglion cells by a whole-cell patch clamp that provides high time resolution. Barium ion was the current carrier, and the channel type studied had a high threshold of activation and fast deactivation (type FD). Block of these channels by 20 microM external Cd2+ is voltage dependent. Cd2+ ions can be cleared from blocked channels by stepping the membrane voltage (Vm) to a negative value. Clearing the channels is progressively faster and more complete as Vm is made more negative. Once cleared of Cd2+, the channels conduct transiently on reopening but reequilibrate with Cd2+ and become blocked within a few milliseconds. Cd2+ equilibrates much more slowly with closed channels, but at a holding potential of -80 mV virtually all channels are blocked at equilibrium. Cd2+ does not slow closing of the channels, as would be expected if it were necessary for Cd2+ to leave the channels before closing occurred. Instead, the data show unambiguously that the channel gate can close when the channel is Cd2+ occupied.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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