title: Muscarinic receptors in isolated guinea pig pancreatic ducts.
abstract: Biochemical and pharmacological characteristics of muscarinic cholinergic receptors in isolated guinea pig pancreatic ducts were determined in the present study. Duct homogenates bound 6.82 +/- 0.69 fmol of [3H]N-methylscopolamine ([3H]NMS)/micrograms of DNA with a Kd of 0.73 +/- 0.05 nM. The density of [3H]NMS binding sites in the excretory ducts was seven times greater than that in acini from the same pancreases. Competition binding studies with atropine, pirenzepine, 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H- pyrido[2,3-b] [1,4]benzodiazepine-6-one (AF-DX 116), and 4-diphenylacetoxy-N-methyl piperidine methiodide (4-DAMP) indicated that both M2 and M3 subtypes of muscarinic receptors are present in these preparations of isolated pancreatic ducts. Electrophoretic analysis of [3H]propylbenzilylcholine mustard-labeled unreduced and reduced duct muscarinic receptors provided molecular mass estimates of 62.6 +/- 2.5 and 58.0 +/- 1.6 kDa, respectively. Deglycosylation of ductal muscarinic receptors with N-glycanase decreased their apparent molecular mass by approximately 4 kDa. These results demonstrate that isolated pancreatic ducts express both M2 and M3 muscarinic receptors, with the former subtype predominating.
authors.affiliation: Department of Physiology, Michigan State University, East Lansing 48824.
authors.forename: S R
authors.initials: SR
authors.lastname: Hootman
authors.forename: J
authors.initials: J
authors.lastname: Zukerman
authors.forename: S A
authors.initials: SA
authors.lastname: Kovalcik
mesh_terms: D000581:Amidohydrolases; D000818:Animals; D001667:Binding, Competitive; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008970:Molecular Weight; D019832:N-Methylscopolamine; D010183:Pancreatic Ducts / Q000378:metabolism*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D010880:Piperidines / Q000494:pharmacology; D011438:Propylbenzilylcholine Mustard; D011976:Receptors, Muscarinic / Q000032:analysis* / Q000737:chemistry / Q000187:drug effects; D012602:Scopolamine Derivatives / Q000494:pharmacology; D014316:Tritium
chemical_list: D010880:Piperidines; D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D014316:Tritium; D011438:Propylbenzilylcholine Mustard; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D019832:N-Methylscopolamine