Interactions of acetylcholine receptors with organic mercury compounds

Adv Exp Med Biol. 1977;84:449-63. doi: 10.1007/978-1-4684-3279-4_20.

Abstract

Micromolar concentrations of methylmercury and several organic mercury fungicides were found to block binding of [3H]acetylcholine (ACh) to the ACh-receptor of the electric organ of the electric ray, Torpedo ocellata. The same compounds had little or no effect on the catalytic activity of ACh-esterase of the same tissue. [14C]Methyl-mercury bound to the purified ACh-receptor with high affinity (Kd=7micrometer) and there were 6.5 +/- 0.5 binding sites for each ACh-binding site. Binding of methylmercury was highly cooperative with a Hill coefficient of 2.6. This binding was irreversible by redialysis in methylmercury - free medium, however, the bound [14C]methylmercury was easily displaced from the receptor protein with micrometer concentrations of BAL or penicillamine. Methylmercury also blocked binding of [3H] nicotine and [3H]pilocarpine to the nicotinic and muscarinic ACh-receptors of the rat brain, respectively. The data suggest that the ACh-receptor may be a target for methylmercury and other organic mercury compounds.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcholine / metabolism*
  • Animals
  • Binding, Competitive
  • Brain / metabolism
  • Brain / ultrastructure
  • Cholinesterase Inhibitors
  • Electric Organ / metabolism
  • Fishes
  • In Vitro Techniques
  • Kinetics
  • Methylmercury Compounds / metabolism
  • Nicotine / metabolism
  • Organomercury Compounds / metabolism*
  • Organomercury Compounds / pharmacology
  • Pilocarpine / metabolism
  • Rats
  • Receptors, Cholinergic / drug effects
  • Receptors, Cholinergic / metabolism*
  • Subcellular Fractions / metabolism

Substances

  • Cholinesterase Inhibitors
  • Methylmercury Compounds
  • Organomercury Compounds
  • Receptors, Cholinergic
  • Pilocarpine
  • Nicotine
  • Acetylcholine