Abstract
Silver has been widely used in various medical products because of its antibacterial properties. However, there is only limited information concerning silver-related cytotoxicity. In this study we show that Ag+ at low nanomolar concentrations (<10 nM) strongly inhibits the activity of large-conductance Ca2+-activated K+ channels (BK) (Slo1), a widely expressed and physiologically important potassium channel. The Ag+ inhibition is caused by irreversible modification on cytosolically accessible parts of the BK channel. At least four intracellular cysteines are involved in this process. In addition, at least one of these key cysteines is not accessible to the bulkier thiolate-active reagent [2-(trimethylammonium)ethyl] methanethiosulfonate bromide. One of the cysteine-less constructs generated in this study shows gating properties similar to wild-type BK channel but with much lower Ag+ sensitivity, in which the Ag+ modification rate was decreased by approximately 20-fold. The results from the present study suggest a possible contribution of BK channel inhibition to the cytotoxicity of Ag+ in humans and other species.
Footnotes
↵ The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
This work was supported by the National Institutes of Health National Institute of General Medical Sciences [Grant GM66315].
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.110.066407.
-
ABBREVIATIONS:
- BK
- large-conductance Ca2+-activated K+ channel
- MTSET
- [2-(trimethylammonium)ethyl] methanethiosulfonate bromide
- MTSES
- sodium (2-sulfanatoethyl) methanethiosulfonate
- NEM
- N-ethylmaleimide
- TBA
- tetrabutylammonium nitrate
- MTS
- methanethiosulfonate
- G-V
- conductance-potential
- [Ca2+]in
- intracellular calcium concentration.
- Received May 14, 2010.
- Accepted August 20, 2010.
- Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|