Identification of three muscarinic receptor subtypes in rat lung using binding studies with selective antagonists

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Life Sciences; (USA)

DOI:https://doi.org/10.1016/0024-3205(90)90572-9· OSTI ID:6796067

Fryer, A D; El-Fakahany, E E ^[1]

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1. Univ. of Maryland, Baltimore (USA)

Heterogeneity of the muscarinic receptor population in the rat central and peripheral lung was found in competition binding experiments against ({sup 3}H)quinuclidinyl benzilate (({sup 3}H)QNB) using the selective antagonists pirenzepine, AF-DX 116 and hexahydrosiladifenidol (HHSiD). Pirenzepine displaced ({sup 3}H)QNB with low affinity from preparations of central airways indicating the absence of M{sub 1} receptors in the trachea and bronchi. Muscarinic receptors in the central airways are comprised of both M{sub 2} and M{sub 3} receptors since AF-DX 116, an M{sub 2}-selective antagonist, bound with high affinity to 70% of the available sites while HHSiD, an M{sub 3}-selective antagonist bound with high affinity to the remaining binding sites. In the peripheral lung, pirenzepine bound with high affinity to 14% of the receptor population, AF-DX 116 bound with high affinity 79% of the binding sites while HHSiD bound with high affinity to 18% of the binding sites. The presence of M{sub 1} receptors in the peripheral airways but not in the central airways was confirmed using ({sup 3}H)telenzepine, an M{sub 1} receptor ligand. ({sup 3}H)Telenzepine showed specific saturable binding to 8% of ({sup 3}H)QNB labeled binding sites in homogenates of rat peripheral lung, while there was no detectable specific binding in homogenates of rat trachea or heart.

• OSTI ID: 6796067
• Journal Information: Life Sciences; (USA), Journal Name: Life Sciences; (USA) Vol. 47:7; ISSN 0024-3205; ISSN LIFSA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BODY
DISTRIBUTION
DRUGS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LIGANDS
LUNGS
MAMMALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
ORGANS
PARASYMPATHOMIMETICS
PROTEINS
RATS
REACTION KINETICS
RECEPTORS
RESPIRATORY SYSTEM
RODENTS
TISSUE DISTRIBUTION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES