Selectivity of cations and nonelectrolytes for acetylcholine-activated channels in cultured muscle cells

Li Yen Mae Huang, William A. Catterall, Gerald Ehrenstein

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The selectivity of acetylcholine (ACh)-activated channels for alkali cations, organic cations, and nonelectrolytes in cultured muscle cells of chicken embryo has been studied. To test the effect of size, charge, and hydrogen-binding capacity of permeant molecules on their permeability, we have obtained the selectivity sequences of alkali cations, compared the permeability of pairs of permanent molecules with similar size and shape but differing in charge, and studied the permeability of amines of different hydrogen bonding capacity. ACh-activated channels transport alkali cations of small hydration radii and high mobility. The molecules with positive charge and (or) a hydrogen-bond donating moiety are more permeable than the ones without. On the other hand, several nonelectrolytes, i.e., ethylene glycol, formamide, and urea, do have a small, but measurable, permeability through the channels. These results are consistent with a model that ACh-activated channel is a water-filled pore containing dipoles or hydrogen bond accepting groups and a negative charged site with a pK of 4.8.

Original languageEnglish (US)
Pages (from-to)397-410
Number of pages14
JournalJournal of General Physiology
Issue number4
StatePublished - Apr 1 1978
Externally publishedYes


ASJC Scopus subject areas

  • Physiology

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