Possible Allosteric Interaction of 4‐Aminopyridine with Rat Brain Muscarinic Acetylcholine Receptors

Wi S. Lai, Vickram Ramkumar, Esam E. El‐Fakahany

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19 Scopus citations

Abstract

The interaction of the potassium channel blocker 4‐aminopyridine (4‐AP) and its analogs with muscarinic acetylcholine receptors was studied in rat brain homogenate. 4‐AP displaced specific [3H]quinuclidinyl benzilate ([3H]QNB) binding in a concentration‐dependent fashion. Hill coefficient values decreased with increasing the concentration of [3H]QNB and different analogs of 4‐AP demonstrated varying potencies. Scatchard analysis of saturation isotherms of specific [3H]QNB binding showed that low concentrations of 4‐AP slightly reduced maximum binding without affecting the equilibrium dissociation constant, whereas higher concentrations reduced maximum binding further and significantly increased the equilibrium dissociation constant. Schild plots of these data resulted in curvilinear functions. The results are discussed in terms of possible allosteric interactions between potassium channels and muscarinic receptor binding sites.

Original languageEnglish (US)
Pages (from-to)1936-1942
Number of pages7
JournalJournal of Neurochemistry
Volume44
Issue number6
DOIs
StatePublished - Jun 1985

Keywords

  • 4‐Aminopyridine
  • Channel blockers
  • Muscarinic receptors
  • Potassium channels

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