The binding of (3H)AF-DX 384 to rat ileal smooth muscle muscarinic receptors

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Journal of Receptor Research; (United States)

DOI:https://doi.org/10.3109/10799899109066395· OSTI ID:5080357

Entzeroth, M; Mayer, N ^[1]

---

1. Department of Biochemical Research, Dr. Karl Thomae GmbH Biberach (West Germany)

The tritiated cardioselective muscarinic antagonist AF-DX 384 (5,11-dihydro-11-(2-(-(8-dipropylamino)methyl)-1-piperidinyl-ethyl-amino-carbonyl)-6H-pyrido (2,3-b) (1,4)benzodiazepin-6-one) was used to label muscarinic receptors in the rat ileum. Saturation binding to membrane suspensions revealed a high affinity binding site with a Kd of 9.2 nM. The maximal number of binding sites labeled in this tissue (Bmax) is 237 fmol/mg protein. The association and dissociation kinetics were well represented by single exponential reactions, and the dissociation constant obtained from the ratio of rate constants was in agreement with that derived from saturation experiments. Specific binding was inhibited by muscarinic antagonists with a rank order of potencies of atropine (pKi: 8.80) greater than 4-DAMP (pKi: 8.23) = AF-DX 384 (pKi: 8.20) greater than AF-DX 116 (pKi: 7.09) = hexahydro-sila-difenidol (pKi: 6.97) greater than pirenzepine (pKi: 6.49) and is consistent with the interaction of (3H)AF-DX 384 with muscarinic receptors of the M2 subtype. It can be concluded that (3H)AF-DX 384 can be used to selectively label M2 muscarinic receptors in heterogeneous receptor populations.

• OSTI ID: 5080357
• Journal Information: Journal of Receptor Research; (United States), Vol. 11:1-4; ISSN 0197-5110
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PARASYMPATHOLYTICS
BIOCHEMICAL REACTION KINETICS
SYMPATHOMIMETICS
RECEPTORS
CPB
MUSCLES
RATS
SMALL INTESTINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
DIGESTIVE SYSTEM
DRUGS
GASTROINTESTINAL TRACT
HYDROGEN COMPOUNDS
INTESTINES
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques