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Biophys J. 1990 May; 57(5): 1085–1090.
PMCID: PMC1280813
PMID: 1692749

Voltage-dependent block by intracellular Mg2+ of N-methyl-D-aspartate-activated channels.

J W Johnson and P Ascher
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Abstract

The N-methyl-D-aspartate (NMDA)-activated channel, which is known to be blocked by extracellular Mg ions, is shown also to be blocked by intracellular Mg ions. The block by intracellular Mg can be explained by assuming that Mg ions from the intracellular side enter the membrane electrical field before binding to the blocking site. The dissociation constant of the binding site for intracellular Mg is 8 mM at 0 mV, which is close to the value previously calculated for the extracellular Mg blocking site. The unbinding rates of intracellular and extracellular Mg are different, and their effects are additive, suggesting that the corresponding binding sites are distinct. Both blocks occur at physiological concentrations of Mg, making the NMDA-activated channel a bidirectional rectifier.

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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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