Kinetic effects of terbium ions on muscarinic acetylcholine receptors of murine neuroblastoma cells

E. E. El-Fakahany, M. Pfenning, E. Richelson

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Abstract

Preincubation of murine neuroblastoma cells (clone N1E-115) with terbium chloride resulted in a significant potentiation of carbachol-mediated increase in cyclic GMP formation. This effect was accompanied by a shift of the peak response from 30 s to 120 s and a 6-fold decrease in carbachol concentration producing half-maximal responses, in addition to a significant increase in the Hill coefficient. Terbium ions also caused a significant decrease in the affinity and an increase in the maximum binding of [3H]quinuclidinyl benzilate to muscarinic receptors, the change in affinity being mainly due to a decrease in the association rate. Preincubation of cells with 1 mM carbachol for 4 h (the desensitized state of the muscarinic receptor) resulted in a decrease in the ability of terbium to alter [3H]quinuclidinyl benzilate binding. The effects of terbium reported here might be due to its affecting muscarinic receptor-effector coupling, which is considered to be lost upon receptor desensitization.

Original languageEnglish (US)
Pages (from-to)863-869
Number of pages7
JournalJournal of Neurochemistry
Volume42
Issue number3
StatePublished - 1984

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ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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