The binding properties of myocardial muscarinic acetylcholine receptors are altered in the presence of choline or Tris. The binding of the antagonist [3H]quinuclidinyl benzilate is reduced in the presence of choline or Tris buffer, when compared to parallel determinations in a physiologic salt solution or phosphate buffer. Scatchard analysis indicates the reduced binding is due to a decrease in the apparent number of receptor sites. Experiments with other organic buffers exclude the possibility that the reduced binding in Tris is due to the absence of sodium ions. In the presence of choline or Tris up to 45% of the receptors are not accessible to [3H]quinuclidinyl benzilate. The remaining sites maintain their high affinity for the antagonist. A heterogeneity of antagonist sites is evident.

Original languageEnglish
Pages (from-to)383-388
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - Jan 29 1982


Dive into the research topics of 'Myocardial muscarinic acetylcholine receptor: Choline and tris unmask heterogeneity of antagonist binding sites'. Together they form a unique fingerprint.

Cite this