Identification of muscarinic receptor subtypes in mouse parotid gland

Eileen L. Watson, Peter W. Abel, Dennis Dijulio, W. Zeng, M. Makoid, Kerry L. Jacobson, Lincoln T. Potter, Frank J. Dowd

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Immunoprecipitation of muscarinic receptors from mouse parotid membranes by specific subtype antisera showed that M3 and M1 receptors represented 75 and 15% of the total number of precipitable receptors, respectively. [N- methyl-3H]methylscopolamine (NMS) labeled a single class of high-affinity binding sites in membranes from parotid glands with a dissociation constant of 0.67 ± 0.02 nM and a maximum binding capacity of 176 ± 15 fmol/mg protein. Competition curves for NMS, atropine, 4-diphenylacetoxy-N- methylpiperidine methiodide (4-DAMP) and para-fluoro-hexahydro-sila-difenidol fit best to a one-site binding model, whereas pirenzepine and methoctramine fit best to a two-site binding model, indicating 76-90% M3 receptors. Results from the use of pirenzepine indicated that the second mouse parotid receptor subtype, unlike that of the submandibular gland, has atypical characteristics for an M1 receptor. The rank order of potency of muscarinic antagonists in inhibiting phosphoinositide turnover and biphasic effects of carbachol on isoproterenol-stimulated adenosine 3',5'cyclic monophosphate (cAMP) accumulation was atropine ≤ 4-DAMP >> pirenzepine > AF-DX 116. A specific M1 antagonist, m1-toxin, had no effect on carbachol augmentation or inhibition of isoproterenol responses. Results suggest that M3 receptors couple to both augmentation and inhibition of stimulated cAMP levels.

Original languageEnglish (US)
Pages (from-to)C905-C913
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3 40-3
StatePublished - Sep 1996
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cell Biology


Dive into the research topics of 'Identification of muscarinic receptor subtypes in mouse parotid gland'. Together they form a unique fingerprint.

Cite this