Binding characteristics of the muscarinic receptor subtype in rabbit pancreas.
The muscarinic receptor in the rabbit pancreas was characterized with the use of the labeled ligand (3H)-(-)-quinuclidinyl-benzylate ((3H)-(-)-QNB). Specific binding of (3H)-(-)-QNB to pancreatic acini was found to be reversible and of high affinity, with an equilibrium dissociation constant (KD) of 68 pmol/l and a receptor density (RT) of 170 fmol/mg protein. Agonist binding behaviour was investigated by displacement of (3H)-(-)-QNB binding by eight agonists like arecoline, arecaïdine-propargylester (APE) and carbachol, yielding only low affinity binding sites. The inhibition of (3H)-(-)-QNB binding by the selective antagonists pirenzepine, hexahydrosiladifenidol (HHSiD) and (11-[2-[diethyl-amino)-methyl)-1-piperidinyl]acetyl)-5,11-dihydro-6H-pyr ido (2,3-b) (1,4) benzodiazepin-6-one) (AF-DX 116) confirmed the M3 nature of the rabbit pancreatic receptor.
van Zwam
A J
AJ
Department of Pharmacology, Catholic University of Nijmegen, The Netherlands.
Willems
P H
PH
Rodrigues de Miranda
J F
JF
de Pont
J J
JJ
van Ginneken
C A
CA
D000818:Animals; D001667:Binding, Competitive; D002217:Carbachol / Q000378:metabolism; D007700:Kinetics; D009116:Muscarine / Q000031:analogs & derivatives / Q000378:metabolism; D010095:Oxotremorine / Q000378:metabolism; D010179:Pancreas / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure*; D010277:Parasympathomimetics / Q000378:metabolism; D010890:Pirenzepine / Q000378:metabolism; D011813:Quinuclidinyl Benzilate / Q000037:antagonists & inhibitors / Q000378:metabolism; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000145:classification* / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
D010277:Parasympathomimetics; D011976:Receptors, Muscarinic; D014316:Tritium; C008446:5-methylfurtrethonium; D010890:Pirenzepine; D010095:Oxotremorine; D011813:Quinuclidinyl Benzilate; D009116:Muscarine; D002217:Carbachol