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Reversible blockade of the calcium-activated nonselective cation channel in brown fat cells by the sulfhydryl reagents mercury and thimerosal

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Abstract

We have used patch-clamp techniques to study the effect of the sulfhydryl group oxidizing agents mercury and thimerosal on calcium-activated nonselective cation channels from brown adipose tissue. 100 nmol/l mercury and 50 μmol/l thimerosal induced a complete block. Blockade could be reversed by reduction of the mercaptide by dithiotreitol (DTT). Mercury was found to be the most potent blocker (IC50-value 21×10−9 mol/l), whereas thimerosal (IC50-value 1.5×10−6 mol/l) was as effective as 3′,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC). The DCDPC effect, however, could not be reversed by DTT, indicating different blocking mechanisms. It is concluded that SH-groups are involved in gating of the calcium-activated nonselective channel.

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Correspondence to Ari Koivisto.

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Koivisto, A., Siemen, D. & Nedergaard, J. Reversible blockade of the calcium-activated nonselective cation channel in brown fat cells by the sulfhydryl reagents mercury and thimerosal. Pflugers Arch. 425, 549–551 (1993). https://doi.org/10.1007/BF00374884

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Key words

  • Brown fat
  • DCDPC
  • Mercaptide
  • Mercury
  • Nonselective cation channel
  • Sulfhydryl reagent
  • Thimerosal